NIST Technical Note 1549

Electromagnetic Airframe Penetration 

Measurements of the FAA’s 737-200 

C. Grosvenor 

D. Novotny 

D. Camell 

G. Koepke 

R.T. Johnk 

N. Canales

NIST Technical Note 1549 

Electromagnetic Airframe Penetration 

Measurements of the FAA’s 737-200

Chriss Grosvenor, David Novotny, Dennis Camell, Galen Koepke 

Electromagnetics Division 

Electromagnetics and Electrical Engineering Laboratory 

National Institute of Standards and Technology 

Boulder, CO 80305-3328 

Robert T. Johnk 

National Telecommunication and Information Agency 

Institute for Telecommunications Sciences 

Boulder, CO 80305-3328 

Seturnino Canales 

Formerly with the National Institute of Standards and Technology 

5857 Scenic Ave. 

Firestone, CO 80504-5652 

March 2010 

U.S. Department of Commerce 

Gary Locke, Secretary 

National Institute of Standards and Technology 

Patrick Gallagher, Director 
National Institute of Standards U.S. Government Printing Office For Sale by the 

and Technology Washington: 2010 Superintendent of Documents 

Technical Note 1549 U.S. Government Printing Office 

Natl. Inst. Stand. Technol. Stop SSOP, Washington, DC 20402-0001

Tech. Note 1549 Phone: (202) 512-1800 

237 pages (March 2010) Fax: (202) 512-2250 

CODEN: NTNOEF Internet: bookstore.gpo.gov 
iii 

Contents 

1. History and Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 

2. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 

3. Initial Simulations, Theoretical Analysis and Measurements. . . . . . . . . . . . . . . . . . . . .5 

3.1 Frequency Averaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

3.2 Ground Bounce and other Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 

 3.2.1 Ground Bounce in a Laboratory Environment. . . . . . . . . . . . . . . . . . . . .10 

 3.2.1.1 Time-of-flight for Direct Antenna Response and . . . . . . . . . . . . . . . . 

 Ground Bounce Response Effects . . . . . . . . . . . . . . . . . . . . . . . . . 10 

 3.2.1.2 Simulating Ground Bounce into a Shielded Enclosure. . . . . . . . . . 11 

 3.2.2 Ground Bounce in an Aircraft Testing Environment. . . . . . . . . . . . . . . .19 

 3.2.3 Effects of Varying Ground Conditions on Antenna Measurements. . . . 21 

 3.2.4 Effects of Ground Bounce for Aircraft Measurements . . . . . . . . . . . . . .23 

3.3 Antenna Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

4. Measurement System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 

5. Measurement of Electromagnetic Airframe Penetration. . . . . . . . . . . . . . . . . . . . . . . .30 

5.1 Reference Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 

6. Aircraft Penetration Measurements — Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 

 6.1 Extrapolation Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 

 6.2 Penetration into aircraft from 45° Extrapolation Line. . . . . . . . . . . . . . . . . . .41 

 6.2.1 Measurements in Flight Deck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 

 6.2.2 Measurements in Front Galley . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44 

 6.2.3 Measurements in Rear Galley. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 

 6.2.4 Measurements in Mid-Passenger Cabin . . . . . . . . . . . . . . . . . . . . . .50

 6.3 Mid-Passenger Cabin Penetration Results. . . . . . . . . . . . . . . . . . . . . . . . . . . .53 

 6.3.1 Single-Position Quadrant Measurements . . . . . . . . . . . . . . . . . . . . .53 

 6.3.2 Rear Quadrant Sector Measurements . . . . . . . . . . . . . . . . . . . . . . . .56 

 6.4 Intercompartmental Insertion Loss Measurements. . . . . . . . . . . . . . . . . . . . . 63 

 6.4.1 Main Cabin to Main Cabin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 

 6.4.1.1 Combined TEM horn antenna positions... . . . . . . . . . . . .63 

 6.4.1.2 Individual TEM horn antenna positions. . . . . . . . . . . . . . 66 
iv 

 6.4.1.3 Combined DRG horn antenna positions... . . . . . . . . . . . .79 

 6.4.1.4 Individual DRG horn antenna positions. . . . . . . . . . . . . . 82 

 

 6.4.2 Main Cabin to Flight Deck. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94 

 6.4.2.1 Combined DRG horn antenna positions... . . . . . . . . . . . 94 

 6.4.2.2 Individual DRG horn antenna positions. . . . . . . . . . . . . . 97 

 6.4.2.3 Combined TEM horn antenna positions... . . . . . . . . . . .106 

 6.4.2.4 Individual TEM horn antenna positions. . . . . . . . . . . . . 109 

 

 6.4.3 Main Cabin to Cargo Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 

 6.4.3.1 Combined DRG horn antenna positions... . . . . . . . . . . .120 

 6.4.3.2 Individual DRG horn antenna positions. . . . . . . . . . . . . 123 

 6.4.3.3 Combined TEM horn antenna positions... . . . . . . . . . . .132 

 6.4.3.4 Individual TEM horn antenna positions. . . . . . . . . . . . . 135 

 6.4.4 Main Cabin to Avionics Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 

 6.4.4.1 Combined DRG horn antenna positions... . . . . . . . . . . .147 

 6.4.4.2 Individual DRG horn antenna positions. . . . . . . . . . . . . 150 

 6.4.4.3 Combined TEM horn antenna positions... . . . . . . . . . . .158 

 6.4.4.4 Individual TEM horn antenna positions. . . . . . . . . . . . . 161 

 

 6.4.5 Cargo Bay to Avionics Bay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 

 6.4.5.1 Combined TEM horn antenna positions... . . . . . . . . . . .169 

 6.4.5.2 Individual TEM horn antenna positions. . . . . . . . . . . . . 173 

 6.4.5.3 Combined DRG horn antenna positions... . . . . . . . . . . .181 

 6.4.5.4 Individual DRG horn antenna positions. . . . . . . . . . . . . 184 

7. Uncertainty Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .192 

8. Summary and Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 

9. References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 
v 

 Appendix A. TEM and DRG Horn Boresight Gain Characteristics. . . . . . . . . .198 

 Appendix B. Number of Positions versus Average Power . . . . . . . . . . . . . . . . .200 

 Appendix C. Whisker-Box Plots for the Bombardier Global. . . . . . . . . . . . . . . . . . 

 5000 and the Beechcraft Premier IA. . . . . . . . . . . . . . . . . . . . . . 203 

 Appendix D. Numerical Modeling of the FAA’s 737-200. . . . . . . . . . . . . . . . . 212 

 Appendix D1. The Reference Box Artifact. . . . . . . . . . . . . . . . . . . . . . 213 

 Appendix D2. Simulation of the FAA’s 737-200. . . . . . . . . . . . . . . . . .218 

 Appendix E. 737-200 Measurement Equipment List. . . . . . . . . . . . . . . . . . . . . 233 

1 

Electromagnetic Airframe Penetration 

Measurements for the FAA 

Passenger Jet 737-200

Chriss Grosvenor, David Novotny, Dennis Camell, and Galen Koepke 

Electromagnetics Division 

National Institute of Standards and Technology 

325 Broadway 

Boulder, CO 80305 

and 

Robert T. Johnk 

National Telecommunication and Information Agency 

Institute for Telecommunication Sciences 

325 Broadway 

Boulder, CO 80305 

and 

Seturnino Canales 

Formerly with NIST 

5857 Scenic Ave. 

Firestone, CO 80504-5652 

The National Institute of Standards and Technology has completed shielding 

effectiveness/penetration studies on three different aircraft types for the Federal Aviation 

Administration. The studies are used to understand the cavity coupling characteristics between 

antennas placed in various compartments inside the aircraft and antennas placed at various 

angular positions around an aircraft. This document shows how penetration varies as a function 

of frequency, antenna type, antenna polarization, and cavity susceptibility for a 737-200 

passenger jet. The document discusses initial numerical analysis, antenna gain dependence, and 

ground bounce effects and how they impact the data. Internal coupling between two antennas 

placed in the aircraft at different locations was studied and a statistical analysis of the insertion 

loss between various compartments is also presented. 

Key words: aircraft; cavity coupling; digital signal processing; HIRF; numerical modeling; 

penetration; shielding effectiveness; synthetic time-domain measurements. 
2 

1. History and Background 

The Federal Aviation Administration (FAA) is responsible for the safety of civilian aviation [1]. 

Included in this function is the responsibility to ensure that the flight hardware is safe from an 

electromagnetic interference (EMI) event that could jam navigational equipment and render 

flight hardware inoperable. The avionics systems are flight critical, and uninterrupted operation 

is required in order to fly the aircraft safely. There is a history of EMI-induced system failures in 

both military and commercial electronic systems [2–5]. This is one of the reasons why 

manufacturers of aircraft are required to submit test data showing that their aircraft can provide 

enough protection or shielding of interior flight systems from outside electromagnetic sources. 

These tests are called high intensity radiated field (HIRF) measurements and are used to 

determine the shielding effectiveness of the aircraft from radiating sources [6–13]. HIRF sources 

are only those emitters that intentionally generate emissions. HIRF sources include radio and 

TV transmitters, airport and weather radar, and various military systems, both ground-based and 

airborne, such as surveillance radar, electronic warfare (EW) systems, and electromagnetic 

weapons. These radiating sources can also include ground tracking radars, electromagnetic pulse 

(EMP) events, both natural and man-made, such as lightning or EMP ordnance, cell phones, 

electrostatic discharge (ESD), and other events. The hazard levels for these interferers have been 

studied [14] and are incorporated into HIRF test methodologies [15]. 

Manufacturer’s HIRF data are given to the FAA for inspection but are often not accompanied by 

a detailed test report as to how the tests were performed. Often the data have very noise-like 

characteristics and are difficult to interpret. The National Institute of Standards and Technology 

(NIST) has had previous experience with measuring the shielding effectiveness of aircraft [16 - 

19]. For this reason, the FAA approached NIST to provide guidance on the interpretation of the 

HIRF measurement results. The project was three-fold: (1) analyze canonical structures by use 

of numerical methods, (2) develop efficient measurement and data-processing methods based on 

the numerically modeled results, and (3) perform an extensive set of measurements on an actual 

aircraft. Once these tasks were completed, the FAA would have a more complete understanding 

of common measurement methods supported by detailed numerical analyses. 

The Field Parameters and EMC Applications Project of the National Institute of Standards and 

Technology (NIST) has now completed shielding effectiveness/penetration studies of three 

representative aircraft for the Federal Aviation Administration (FAA). These studies will 

provide the FAA with the procedures and data-reduction techniques for typical low-signal-level 

airframe penetration for high-intensity radiated field (HIRF) attenuation/shielding tests. This 

technical note addresses aircraft shielding tests conducted on a 737-200 passenger jet owned and 

operated by the FAA. Two additional reports have been completed involving studies of (1) a 

Bombardier Global 5000 business jet owned and operated by the FAA [18] and (2) a Beechcraft 

Premier IA owned by the Hawker-Beechcraft Corporation [19]. The Bombardier Global 5000 

represents a commercial business jet, and the Premier IA represents a typical carbon-composite 

aircraft. By measuring all three aircraft and comparing them, we have the potential to provide a 

“design roadmap” for the optimization of HIRF testing standards for the electromagnetic 

compatibility (EMC) aircraft manufacturing community. 
3 

The FAA currently has specific certification policies addressing the effects of HIRF on an 

aircraft’s electrical and electronic systems that have been applied since around 1990 [15]. This 

document is presently being rewritten, and a new draft is expected to be completed in 2010. In 

the current FAA document, the regulatory authorities and industry have defined HIRF 

environments, requirements for aircraft HIRF protection, and methods for testing and verifying 

the level of HIRF protection. Most of reference [15] discusses HIRF testing for electronic and 

electrical subsystems, which this technical note does not address. In this technical note, we 

specifically address both high- and low-level airframe shielding compliance testing. The HIRF 

procedures are found in Section 6.6.2.6 and Section 6.6.4 of Reference [15]. 

The basic problem is to evaluate the coupling of an external source into a large, 

electromagnetically leaky cavity [20 – 27]. The cavity could represent the whole aircraft or part 

of it (cargo bay, flight deck, etc.), depending on the expected vulnerability. In a typical HIRF 

measurement, the measurement system is calibrated, and a reference measurement is taken 

without the aircraft embedded in the test setup. The aircraft is then placed into the test setup and 

various measurements are taken in susceptible cavities. These attenuation tests are typically 

conducted by use of either mechanical stirring or frequency-stirring methods [13–15]. The 

airframe attenuation is calculated by use of the following equation: 

. . , (1) reference measurement A SE atten cavity measurement  

where Aatten is the airframe attenuation and S.E. is defined as the shielding effectiveness. These 

numbers, expressed in decibels, are typically positive, so that the more positive the number, the 

greater the protection the aircraft provides to electromagnetic fields, and as the number 

approaches zero we expect almost no shielding protection. The aircraft HIRF attenuation data 

vary as a function of frequency, physical position of the measurement antenna, angle of 

incidence, polarization, characteristics of the aircraft, and configuration of the test site. After a 

company tests and processes the data, the information is given to the FAA, which uses it in 

conjunction with the subsystem susceptibility tests to determine an aircraft’s HIRF vulnerability. 

The detailed method used to process aircraft HIRF attenuation data is not well documented and 

is closely held by the handful of test service providers. Therefore, the interpretation of the data 

is not immediately obvious to the certification engineer. This technical note and the previous 

two technical notes consider attenuation measurements as a function of frequency, antenna 

position, antenna type, and cavity selection. Our data-processing methodology will be shown in 

detail. Using this information, we hope to provide guidelines for both the FAA and test 

engineers to develop a uniform and transparent test method for data processing and 

documentation. We know that the confidence levels are expected to depend on the number of 

sample points (measurement geometries), but we should be able to assess the trade-offs between 

measurement effort (sample number) and risk (confidence level). 

 
4 

2. Overview 

This report summarizes results of two measurement efforts conducted by the Field Parameters 

and EMC Applications Project team of NIST. This effort consisted of an extensive series of 

penetration, internal, and ground-condition measurements performed on a 737-200 passenger jet 

owned and operated by the FAA. The aircraft was tested at the FAA site in Atlantic City, New 

Jersey during two periods from October 2004 to October 2005. The purpose of these efforts is to 

provide the FAA with a database of penetration and insertion loss data on the 737-200 passenger 

jet. 

Both efforts utilized NIST-developed measurement systems consisting of ultra-wideband 

transverse electromagnetic (TEM) horn antennas, 3115 dual-ridged guided (DRG) horn antennas, 

commercially available vector network analyzers (VNAs), interconnecting transmission media, 

and an amplifier for the second effort. The first effort measured penetration from approximately 

100 MHz to 2.5 GHz. Interconnections between transmitting and receiving antennas were made 

using an 11 GHz precision, analog electro-optic link. The second effort combined both the 

11 GHz and the 18GHz precision, analog electro-optic links. These efforts were the first time 

NIST researchers used a broadband, analog, electro-optic link with a COTS (commercially 

available off-the-shelf) VNA for airframe shielding studies up to 18 GHz. Shielding data were 

obtained from a direct comparison of two measurements: (1) a transmission measurement 

between boresighted antennas located outside the aircraft to obtain a reference, and (2) 

transmission measurements with one antenna located inside a selected compartment of the 

aircraft and a pair of horizontally and vertically polarized antennas for both low-frequency-band 

and high-frequency-band antennas located outside the aircraft at specified locations. Shielding 

data were obtained by comparing processed reference and aircraft transmission data. This was 

achieved by use of an efficient sequence of Fourier and inverse Fourier transformations, 

frequency domain convolutions, and filtering combined with time gating and frequency 

averaging. Shielding values were obtained by taking the ratio of the gated amplitude spectra of 

the aircraft measurement and the gated amplitude spectra of the references. Data smoothing was 

performed by use of the frequency-averaging of signal power over a specified bandwidth as 

described in [16]: 

 

2 1 ( ) . (1) 2 1

n N

n i

inN

SE f SE f N



 

 



Shielding data were obtained with a receiving antenna located in one of four internal 

compartments: (1) the main passenger cabin, (2) the flight deck, (3) the cargo bay, and (4) the 

avionics bay. A pair of transmitting antennas was positioned outside the aircraft at a fixed height 

of approximately 5 m, which is the approximate height of the windows, at a fixed distance of 

23 m from the center of the aircraft. The transmitting antennas were boresighted at the center of 

the aircraft, and data were obtained for both the horizontal and vertical polarizations. We based 

our tests on HIRF standard test procedures and other questions we felt were important to ask. 

These standards are concerned with detecting possible leakage into the aircraft. Key areas 

include the flight deck, the avionics bay, any windows/doors/joints, and the wing/tail section of 

the fuselage. During our first effort, we developed a test plan designed to understand the effect of 
5 

varying ground conditions on the data [28], and how many positions are necessary to fully 

characterize an electrically large object and to fully characterize the fields penetrating into the 

aircraft for a particular high-frequency limit [29–32]. For this reason, we included a number of 

angular positions to study penetration apertures around the aircraft and at six positions around 

the rear one-fourth sector of the aircraft at a constant distance from the center of the aircraft. 

Finally, we concluded with an extensive set of internal coupling measurements designed to 

understand the interaction between compartments and the reverberation characteristics of the 

aircraft. This first effort consisted of the following measurements: (1) Extrapolation 

measurements at 6.1 m (20 ft.), 9.1 m (30 ft.), 12.1 m (40 ft.), 15.2 m (50 ft.), 23.5 m (75 ft.), and 

30.1 m (100 ft.); (2) Extrapolation measurements at 15.2 m, 23.5 m, and 30.5 m for ground 

conditions including the tarmac and a sheet of rFoil (radiant barrier foil), which consists of a 

layer of polyethylene bubbles bonded to and sandwiched between two highly reflective surfaces 

[33], for both vertical and horizontal polarization; (3) sector measurements at 90°,100°, 110°, 

120°, 125°, 130°, 135°, 140°, 145°, 150°, 160°, 170° and 180° to look at the angular dependence 

of radiating apertures. Finally, in the first effort, we concluded with a set of internal coupling 

measurements to understand the reverberant environment internal to the aircraft. An aircraft’s 

level of electromagnetic field protection, referred to as shielding, depends on the level of 

treatment, the compartment, the frequency, the transmitting antenna polarization, and the angle 

of illumination. In this document, we will display penetration values, which are the reciprocal of 

shielding values. In the graphs that follow, a penetration near 0 dB means electromagnetic fields 

can easily penetrate into that part of the aircraft. Penetration levels for the FAA’s Boeing 737-

200 commercial aircraft range from approximately −10 dB to −40 dB. The dynamic range of 

this system is a function of the compartment in which it is located. For the system in the main 

cabin, the estimated dynamic range is −70 dB at 1000 MHz and −50 dB at 3000 MHz. For the 

system in the cargo bay, the estimated dynamic range is −60 dB at 1000 MHz and –40 dB at 

3000 MHz. 

This report is divided into five main sections: (1) Initial theoretical and simulation analysis, (2) a 

description of the measurement system, (3) an overview of the measurement technique, (4) an 

overview of the signal processing, (5) a summary of results for the four different aircraft 

compartments and various internal measurements, and (6) an uncertainty analysis. Appendices 

A through E discuss the number of positions versus the average power, whisker-box plots 

showing how frequency bandwidths affect the statistics of the Bombardier Global 5000 and 

Beechcraft Premier IA results, simple numerical modeling results, an equipment list, and the gain 

characteristics of the ultra-wideband antennas that were used. 

3. Initial Simulations, Theoretical Analysis, and Measurements 

3.1 Frequency averaging 

We began these efforts by doing some theoretical analysis to understand the importance of 

certain parameters and their impact on aircraft measurements. An initial finite-difference, timedomain (FDTD) model was developed for a pulsed source in free-space. Other models have 

been developed for HIRF radiation levels [20–21]. Figure 1 shows the time-domain waveform 

that results from the model. The electromagnetic fields can be seen emanating from the pulsed 

source on the left to a monitor point on the right. A plot showing the initial time-domain pulse is 
6 

shown on the right. The onset of the impulse occurs at around 20 ns and the impulse response is 

around 2 ns. We then modeled a slot in an infinite ground plane as shown in Figure 2. The 

pulsed source was on one side of the infinite ground plane, and the monitor point was on the 

other. The frequency-domain waveform corresponding to Figure 2 is shown in Figure 3. The 

plot shows the resonances that result from the electromagnetic waves penetrating through the slot 

and being received at the monitor point. 

The next model took a portion of the infinite ground plane with the slot and backed it with a box 

based on the dimensions of a reverberant box designed by NIST and the Naval Surface Warfare 

Center. The dimensions were selected to permit sufficient modal density above 1 GHz, to 

achieve reverberant behavior inside the box, and to exhibit characteristics of an electrically large 

cavity (see Figure 4). Aluminum was chosen for fabrication ease and its high electrical 

conductivity. A rotatable aluminum paddle, powered by an external d.c. motor, was installed 

within the box to provide mode-stirring. Five holes 1.6 cm in diameter were randomly punched 

on each side of the box. We chose this diameter so that all apertures were electrically small from 

2 GHz to 4 GHz and to achieve a shielding effectiveness in the range of 20 dB to 30 dB. This 

range of shielding values is based on theoretical guidelines and was verified by use of 

measurements performed in the reverberation chamber [25]. The FDTD box model is shown in 

Figure 5. The time-domain and frequency-domain signatures of the slotted box problem are 

shown in Figures 6 and 7. The time-domain figures show that the signal reaches the monitor 

point starting at around 25 ns. From this time forward we obtain a slowly decaying electric field 

amplitude. When an Fast-Fourier Transform (FFT) is applied to the time-domain waveform we 

obtain the frequency-domain plot, also shown in Figure 6. The result shows a noisy looking 

waveform where not much important information is available. To bring out important details 

and minimize the noise, we averaged the frequency-domain data over a small bandwidth of 

frequencies [16]. Figure 7 shows the result of frequency averaging for bandwidths of 50 MHz 

and 100 MHz, respectively. The wider the bandwidth the greater the effect of smoothing the 

data; however, we do see that the original resonances that occurred for the slit in the infinite 

round plane are now revealed. 

20 30 40 50 60

Time (ns)

-4000

-2000

0

2000

4000

Ey (V/m)

Monitor

Point

Pulsed

Source

Figure 1. FDTD Modeling and result for pulsed source in free space.
7 

 

Pulsed

Source

Monitor

Point

Resonant 

Slot

Figure 2. Resonant slot in an infinite ground plane.

0 1000 2000 3000

Frequency (MHz)

-60

-50

-40

-30

-20

-10

0

Penetration (dB)

Slot Resonances

Figure 3. Slot resonances from a slit in an infinite 

ground plane.
8 

Figure 4. Aluminum reverberant box designed to

simulate 20 to 30 dB of shielding.

Monitor

Point

Coupling

Aperture

Pulsed

Source

Figure 5. FDTD Model of the NIST/Naval Surface Warfare Center

Shielded Enclosure.
9 

0 100 200 300 400 500

Time (ns)

-150

-100

-50

0

50

100

150

Ey (V/m)

0 1000 2000 3000

Frequency (MHz)

-80

-60

-40

-20

0

20

Penetration (dB)

Figure 6. Time-domain and frequency-domain waveforms for a pulsed source in a slotted box.

0 100 200 300 400 500

Time (ns)

-150

-100

-50

0

50

100

150

Ey (V/m)

0 1000 2000 3000

Frequency (MHz)

-80

-60

-40

-20

0

20

Penetration (dB)

0 100 200 300 400 500

Time (ns)

-150

-100

-50

0

50

100

150

Ey (V/m)

0 1000 2000 3000

Frequency (MHz)

-80

-60

-40

-20

0

20

Penetration (dB)

Figure 6. Time-domain and frequency-domain waveforms for a pulsed source in a slotted box.

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

10

Penetration (dB)

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

10

Penetration (dB)

50 MHz 100 MHz

Figure 7. A 50 MHz and 100 MHz frequency averaging bandwidth applied to the waveform in Figure 6.
10 

3.2 Ground Bounce and other Effects 

3.2.1 Ground Bounce in a Laboratory Environment 

3.2.1.1 Time-of-flight for direct antenna response and ground bounce response 

The effect of ground bounce and ground conditions are important when one measures 

penetration into an aircraft either sitting on a hangar floor or on the tarmac [28]. This is because 

ground bounce is not an effect seen when an aircraft is in flight as the electromagnetic radiating 

field impinges on the aircraft. Ideally, the aircraft should be measured in flight to avoid these 

types of effects; however costs and ease of measurements are impractical. To understand the 

effect of ground bounce on our measurements, we began with the following analysis. We 

measure the transmission in our laboratory for two 1.2 m TEM horn antennas. These antennas 

have a short impulse response [34], so the initial direct antenna-to-antenna response can be 

isolated from the response due to the interaction with the ground, also known as ground bounce. 

A diagram showing the measurement setup is shown in Figure 8. From the geometry, we can 

determine the signal delay from one antenna to another for both the direct component and the 

ground-bounce component. If the antenna apertures are separated by 1.9 m and the additional 

delay due to 15 cm of cable and the antenna transition from the end of one calibration reference 

plane to another is taken into account, then the time of flight for the direct signal response will be 

approximately 23 ns. We can compute the time of flight for the ground-bounce component by 

knowing that the aperture center of the antenna was 1.7 m above the ground plane. The 

geometrical calculations tell us that the signal due to ground bounce should arrive at 

approximately 27 ns. Figure 9 shows two time-domain responses for the direct transmission 

component and the ground-bounce component. The black trace shows an initial direct 

Figure 8. Laboratory setup for transmission measurement between 1.2 m TEM horn antennas.

1.9 m

1.2 m TEM

horn antennas

Styrofoam

supports

Ground plane

1.7 m
11 

component for signal transmission between the antennas and a second component due to the 

ground bounce. If absorber is placed on the ground plane between the antennas, then the red 

trace shows that the ground bounce has been minimized due to the presence of the absorber. By 

looking at the initial time for both responses, we see that the direct antenna-to-antenna impulse 

response begins at around 23 ns and the response due to the ground plane reflection occurs at 

around 27 ns, just as our geometrical ray-tracing model predicted. 

3.2.1.2 Simulating ground bounce into a shielded enclosure 

To look at ground-bounce effects and how they impact measurements into a shielded cavity, we 

set up a shielded cavity in our laboratory at NIST. The measurement setup is shown in Figure 

10. A reference measurement was taken with the antennas at a height of 1.50 m and separated by 

a distance of 2 m. The antenna was placed inside the box (aperture facing the door), and another 

measurement with the door of the box fully open was taken. The door of the box was closed 

until a 15.24 cm (6 in.) gap existed at the top, and a measurement was taken. More 

measurements were taken with a 7.62 cm (3 in.) and a 2.54 cm (1 in.) gap. One measurement 

was taken with the antenna facing toward the back of the shielded box. The antenna was 

lowered on the tripod to a height of 1.35 m and measured with the 15.24 cm, 7.62 cm, and 

2.54 cm gaps. Again the antenna was lowered to a height of 1.21 m and measurements of the 

same door gaps were taken. A time-domain reference waveform is shown in Figure 11 for two 

DRG horn antennas mounted on tripods and separated by a distance of 2 m at a height of 1.5 m. 

10 20 30 40

Time (ns)

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

Amplitude (S21)

1.2 m TEM Horns

(Vpol - Horn 1 to Horn 2)

with absorber

no absorber

Figure 9. Typical reference measurement setup for 1.2 m TEM horn 

antennas on a laboratory ground plane. Distances are shown for the 

direct path and the secondary ground-bounce path.

10 20 30 40

Time (ns)

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

Amplitude (S21)

1.2 m TEM Horns

(Vpol - Horn 1 to Horn 2)

with absorber

no absorber

Figure 9. Typical reference measurement setup for 1.2 m TEM horn 

antennas on a laboratory ground plane. Distances are shown for the 

direct path and the secondary ground-bounce path.
12 

The red box shows the direct antenna-to-antenna response and the blue box shows the groundbounce response. The antennas were placed into the shielded enclosure with the front door to the 

box fully open, and the time-domain waveform, shown in Figure 12, was acquired. Differences 

between the two waveforms can be seen due to the presence of the box, but the ground-bounce 

Figure 10. Measurement setup for ground-bounce experiment.

2 m

Shielded Box

Ground Plane 1.21 m

1.35 m

1.50 m

Figure 10. Measurement setup for ground-bounce experiment.

2 m

Shielded Box

Ground Plane 1.21 m

1.35 m

1.50 m

2 m

Shielded Box

Ground Plane 1.21 m

1.35 m

1.50 m

Figure 11. Time-domain reference waveform for two 

DRG antennas separated by 2 m. 

0 10 20 30 40

Time (ns)

-0.02

-0.01

0

0.01

0.02

S21 Signal Amplitude

Direct Antenna to Antenna Response

Ground Bounce
13 

response is still visible. The frequency spectrum for the two DRG antennas on tripods is shown 

in Figure 13. The black trace shows the frequency spectrum for the entire captured waveform 

including the direct antenna-to-antenna response and ground-bounce response. The red trace 

shows the frequency spectrum of the direct response only (the ground bounce has been timegated out). The blue trace shows the frequency spectrum of the ground bounce with the direct 

response gated out. The separate, gated components (the direct antenna-to-antenna response and 

the ground bounce component) were then added together to see whether we obtained the original 

frequency spectrum. This is shown in Figure 14. The full spectrum is shown by the black trace, 

which includes all frequency responses including the laboratory environment. The separated, 

gated, ground-bounce component added to the gated, direct component is shown by the red trace. 

The extra noise-like behavior on the black trace is due to the laboratory’s response. 

Then we wanted to investigate the waveforms as the door to the shielded enclosure was shut 

incrementally. The ground bounce will begin to be unseparable from the initial impulse response 

of the antenna. However, if we assume that the ground bounce response occurs at the same time 

and we gate this part of the waveform from the total response, what happens to the frequency 

spectrum? Figure 15 shows the time-domain responses for a DRG antenna in the shielded box 

with the door open 15.24 cm and the transmitting antenna at a height of 1.5 m and 1.21 m, 

respectively. Figure 16 shows the time-domain responses for a DRG antenna in the shielded box 

with the door open 2.54 cm and the transmitting antenna at a height of 1.5 m and 1.21 m, 

respectively. The location where the ground bounce is expected is shown by the blue box as in 

Figures 11 and 12. The frequency spectra for the reference measurement (black trace) and the 

respective shielded box waveforms (blue trace) were plotted and are shown in Figure 17 for the 

shielded box door open 15.24 cm and the transmitting antenna at a height of 1.5 m and 1.21 m, 

respectively. Figure 18 shows the frequency spectra for the shielded box door open 1 inch and 

the transmitting antenna at a height of 1.5 m and 1.21 m, respectively. The direct spectrum of 

the reference and the shielded box was overlaid with the ground bounce gated out for both 

measurements. The direct antenna-to-antenna reference is shown by the red trace, and the direct 

antenna-to-antenna response for the shielded box is shown by the green trace. The conclusion 

for these measurements is that the ground bounce affects only the frequency content of the 

waveform and not the amplitude. Figure 19 shows data from the reference measurement and 

Figure 20 shows the results from the shielded cavity measurements. These graphs show the 

relationship between the direct component, the ground bounce component, and the laboratory or 

cavity response. Figure 19 shows the entire waveform (black trace), including the ground 

bounce, laboratory and direct antenna-to-antenna responses, a waveform (red trace) with the 

ground bounce and laboratory responses gated out, leaving just the direct antenna-to-antenna 

response, the laboratory response (blue trace) with the direct and ground bounce gated out, and a 

corresponding system noise floor. Figure 19 shows the same information but with the shielded 

cavity. The additional traces show the shielded cavity direct antenna-to-antenna component plus 

ground bounce and cavity response (light blue trace), and direct-to-direct antenna response with 

shielded cavity (green trace). The purple trace, in this case, is the shielded cavity response with 

the direct antenna-to-antenna response and ground bounce both gated out. 
14 

0 10 20 30 40

Time (ns)

-0.02

-0.01

0

0.01

0.02

S21 Signal Amplitude

Direct Antenna to Antenna Response

Ground Bounce

Figure 12. Time-domain reference waveform for one 

DRG antenna on a tripod and the other in the shielded 

box, separated by 2 m. 

Figure 13. Frequency-domain reference waveform for two DRG antennas 

separated by 2 m. The black trace is the spectrum that includes the direct 

response and ground bounce; the red line is the spectrum of the direct 

response only; the blue line shows the spectrum of the ground bounce.

0 2000 4000 6000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

2 m Reference

Direct Antenna-to-Antenna Response

Ground Bounce Response Only

Figure 13. Frequency-domain reference waveform for two DRG antennas 

separated by 2 m. The black trace is the spectrum that includes the direct 

response and ground bounce; the red line is the spectrum of the direct 

response only; the blue line shows the spectrum of the ground bounce.

0 2000 4000 6000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

2 m Reference

Direct Antenna-to-Antenna Response

Ground Bounce Response Only
15 

0 2000 4000 6000

Frequency (MHz)

-40

-36

-32

-28

-24

-20

S21 Magnitude (dB)

Direct Antenna Component and Ground Bounce

Gated Direct Component added 

 to the Gated Ground Bounce Component

Figure 14. Frequency-domain waveforms for the full spectrum (red trace) 

compared to the gated, ground-bounce component added to the gated, direct 

component.
16 

0 10 20 30 40

Time (ns)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

S21 Signal Amplitude

Ground Bounce

 location from initial file

0 10 20 30

Time (ns)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

S21 Signal Amplitude

Ground Bounce

 location from initial file

1.21 m height 1.50 m height

Figure 15. Time-domain waveforms for a DRG antenna in shielded box with transmit antennas 

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 15.24 cm.

0 10 20 30 40

Time (ns)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

S21 Signal Amplitude

Ground Bounce

 location from initial file

0 10 20 30 40

Time (ns)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

S21 Signal Amplitude

Ground Bounce

 location from initial file

1.21 m height 1.50 m height

Figure 16. Time-domain waveforms for a DRG antenna in shielded box with transmit antennas 

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm.
17 

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 2.54 cm 

 121 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 2.54 cm

 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

Figure 18. Frequency domain waveforms for a DRG antenna in shielded box with transmit antennas 

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm (1 in.).

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 2.54 cm 

 121 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 2.54 cm

 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

Figure 18. Frequency domain waveforms for a DRG antenna in shielded box with transmit antennas 

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm (1 in.).

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 2.54 cm

 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

Figure 18. Frequency domain waveforms for a DRG antenna in shielded box with transmit antennas 

at a height of 1.5 m and 1.21 m, respectively, and the door of the box open 2.54 cm (1 in.).

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 15.24 cm 

 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 15.24 cm 

 121 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

1.21 m height 1.50 m height

Figure 17. Frequency domain waveforms for a DRG antenna in shielded box with transmit 

antennas heights of 1.5 m and 1.21 m, respectively, with the door of the box open 15.24 cm (6 

in.).

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 15.24 cm 

 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 15.24 cm 

 121 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

1.21 m height 1.50 m height

Figure 17. Frequency domain waveforms for a DRG antenna in shielded box with transmit 

antennas heights of 1.5 m and 1.21 m, respectively, with the door of the box open 15.24 cm (6 

in.).
18 

Figure 19. Frequency spectrum showing the 2 m reference 

measurement showing how the various components of the signal 

add and subtract.

0 2000 4000 6000

Frequency (MHz)

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Direct Antenna Component and Ground Bounce

Gated Direct Component added 

to the Gated Ground Bounce Component

Laboratory Response

System Noise Floor

Figure 19. Frequency spectrum showing the 2 m reference 

measurement showing how the various components of the signal 

add and subtract.

0 2000 4000 6000

Frequency (MHz)

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Direct Antenna Component and Ground Bounce

Gated Direct Component added 

to the Gated Ground Bounce Component

Laboratory Response

System Noise Floor

Figure 20. Frequency spectrum showing results of shielded box 

experiment at 150 cm height – door open. Cavity response is found 

by subtracting the gated ground bounce from the full spectrum.

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 

 - 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

Cavity Response

System Noise Floor

Figure 20. Frequency spectrum showing results of shielded box 

experiment at 150 cm height – door open. Cavity response is found 

by subtracting the gated ground bounce from the full spectrum.

0 2000 4000 6000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

S21 Magnitude (dB)

Reference at 2 m

Antenna in Box - Door Open 

 - 150 cm Xmit Height

Reference - Direct Only

Antenna in Box 

 Ground Bounce Removed

Cavity Response

System Noise Floor
19 

3.2.2 Ground Bounce in an Aircraft Testing Environment 

To take the understanding we gained from the laboratory, we can apply a similar analysis for an 

aircraft as was done in Section 3.2.1.1. A schematic is shown in Figure 21 of a measurement 

where the antennas are located at approximately 4 m above the tarmac at the FAA’s Atlantic City 

location. In a typical reference measurement, the antennas are located on a tower 4 m above the 

tarmac and separated by 23.0 m (75 ft.). Performing the same geometrical analysis as above, we 

determine that the time of flight should be around 76 ns for the direct antenna-to-antenna 

response, and the ground reflection should appear around 81 ns. Figure 22 is a time-domain plot 

of an actual reference measurement taken at the FAA Atlantic City facility showing a direct 

antenna-to-antenna component around 74 ns and a ground-bounce component around 76.5 ns. 

Typically in this type of reference measurement we time-gate out the reflection due to the ground 

bounce, which transforms this measurement into a free-space reference. This free-space 

reference is then used to deconvolve antenna effects from the measurement to get aircraft 

penetration values. If we try to time-gate out the ground bounce from our aircraft measurement 

(prior to deconvolution) we run into problems. Since we try to maintain the same antenna 

separations for an antenna inside the aircraft, we can assume that the ground bounce will again 

appear at around 77 ns, and the initial antenna-to-antenna response should be seen at around 

74 ns. A time-domain plot of a measurement at the 70 degree position for the receive DRG horn 

antenna located in the main passenger cabin is shown in Figure 23. In this figure, we see that the 

initial response occurs at approximately 73 ns, and what appears to be a secondary response 

occurs at around 90 ns, which is a delay of 13 ns from where we would expect the ground 

bounce to show up in our measurement. This would result in a geometrical difference of 

approximately 4 m or 12 ft. This analysis suggests that the secondary response is due not to 

ground bounce but to some other interaction of the electromagnetic waves with either the aircraft 

or something internal to the aircraft, and therefore the ground bounce is contained within the first 

initial decay response and cannot be gated out of the measurement. 

Transmitting 

antennas

5 m

Optical Fiber

Receiving 

antennas

5 m

Reference Measurement

22.86 m

Direct antenna-to-antenna 

coupling path (d1 = 22.86 m)

Secondary

Ground bounce

Path

(d2 = 24.952 m)

Figure 21. Schematic showing typical measurement setup 

for a reference measurement between antenna towers.

Transmitting 

antennas

5 m

Optical Fiber

Receiving 

antennas

5 m

Transmitting 

antennas

5 m

Optical Fiber

Receiving 

antennas

5 m

Reference Measurement

22.86 m

Direct antenna-to-antenna 

coupling path (d1 = 22.86 m)

Secondary

Ground bounce

Path

(d2 = 24.952 m)

Figure 21. Schematic showing typical measurement setup 

for a reference measurement between antenna towers.

Reference Measurement

22.86 m

Direct antenna-to-antenna 

coupling path (d1 = 22.86 m)

Secondary

Ground bounce

Path

(d2 = 24.952 m)

Reference Measurement

22.86 m

Direct antenna-to-antenna 

coupling path (d1 = 22.86 m)

Secondary

Ground bounce

Path

(d2 = 24.952 m)

Figure 21. Schematic showing typical measurement setup 

for a reference measurement between antenna towers.
20 

10.528m

-1 0 .5 8 0 m

-8 .0 0 0 m

-6 .0 0 0 m

-4 .0 0 0 m

-2 .0 0 0 m

0.000

2.000m

4.000m

6.000m

8.000m

72.0 72.5 73.0 73.5 74.0 74.5 75.0 75.5 76.0 76.5 77.0 77.5 78.0

T ime Gra p h

Figure 22. Time-domain graphs for DRG Hpol antennas showing the direct antenna-toantenna response and the secondary reflection due to the ground for an antenna separation of 

approximately 23 m and an antenna height of 4 m.

10.528m

-1 0 .5 8 0 m

-8 .0 0 0 m

-6 .0 0 0 m

-4 .0 0 0 m

-2 .0 0 0 m

0.000

2.000m

4.000m

6.000m

8.000m

72.0 72.5 73.0 73.5 74.0 74.5 75.0 75.5 76.0 76.5 77.0 77.5 78.0

T ime Gra p h

Figure 22. Time-domain graphs for DRG Hpol antennas showing the direct antenna-toantenna response and the secondary reflection due to the ground for an antenna separation of 

approximately 23 m and an antenna height of 4 m.

441.054u

-4 28 .27 2 u

-3 00 .00 0 u

-2 00 .00 0 u

-1 00 .00 0 u

0.000

100.000u

200.000u

300.000u

400.000u

50.0 75.0 100.0 125.0 150.0 175.0 200.0

T im e Gra p h

Figure 23. A time-domain plot showing a 23 m measurement for a transmitting DRG Hpol

antenna at the 70 degree position and a DRG receiving antenna in the main passenger cabin.

441.054u

-4 28 .27 2 u

-3 00 .00 0 u

-2 00 .00 0 u

-1 00 .00 0 u

0.000

100.000u

200.000u

300.000u

400.000u

50.0 75.0 100.0 125.0 150.0 175.0 200.0

T im e Gra p h

Figure 23. A time-domain plot showing a 23 m measurement for a transmitting DRG Hpol

antenna at the 70 degree position and a DRG receiving antenna in the main passenger cabin.
21 

3.2.3 Effects of varying ground conditions on antenna measurements 

What happens when measurements are performed over the earth when the surface changes from 

earth or pavement to metal? This question was answered on a previous measurement effort at 

the GM Proving Grounds in March 2004. 

We went to understand the problems they were experiencing with field uniformity on their large, 

outdoor automotive test antenna range [35–37] due to varying ground conditions along the 

measurement path. The antenna range is shown in Figure 24. To study this problem, a 

numerical simulation was developed for the FM (frequency modulation) band from 88 MHz to 

108 MHz. Two different ground conditions were modeled. The first was “earth”, consisting of a 

semi-infinite asphalt medium, having a relative permittivity ε' = 5, relative permeability μ' = 1.0, 

and a conductivity of σ = 0.01 Siemens/m. A 5 m by 5 m perfectly conducting ground plane was 

then placed over the ground to simulate the turntable found inside the measurement radome at 

the GM facility. The simulated environment is depicted in Figure 25. A 1.5 m long transmitting 

dipole was positioned above the “earth” interface or ground plane at a height of 2 m. The results 

of the simulation are shown in Figure 26 with the dipole in the horizontal polarization. Figure 

26a shows the “earth” ground and that interactions with the “earth” ground are minimal. When a 

ground plane is added over the earth, the field uniformity is minimally disrupted as shown in 

Figure 26b. The fields looking down from the dipole over the ground plane are shown in Figure 

26c. The results for the dipole in the vertical polarization of this simulation are shown in Figure 

27. For the “earth”, Figure 27a shows uniform fields tilting slightly upwards. When the ground 

plane is installed, the field uniformity is greatly disturbed, as shown in Figure 27b. The fields 

looking down from the dipole over the ground plane are shown in Figure 27c. These simulations 

show that dissimilar ground interfaces along the measurement path disrupt the fields more than 

just having a single continuous ground interface. 

Figure 24. Outdoor Automotive Antenna Test Range.
22 

Figure 25. Simulation of GM Turntable over an asphalt dielectric medium.

5m

5m Perfectly Conducting

Ground Plane

Real Ground

Epsr = 5.0

Sigma = 10mS/m

1.5m Long Transmitting Dipole

Located 2m high &

X=214m down range

x

z

y

(a) (b) (c)

Figure 26. Simulation of GM turntable over an asphalt dielectric medium. The dipole is in the horizontal 

polarization. The results in (a) show the field uniformity above “earth”. The results in (b) show the field 

uniformity above a 5 m by 5 m “turntable”. The results in (c) are the fields looking down from the dipole over the 

ground plane.
23 

3.2.4 Effects of ground bounce for aircraft measurements 

To understand how ground conditions affect the measurements, we decided to investigate the 

difference between reflections from the tarmac and reflections from a sheet of rFoil. The 

measurement setup is shown in Figure 28. These measurements were taken along the 45° 

extrapolation line (Figure 44) at distances of 15.2 m (50 ft.), 23.5 m (75 ft.), and 30.5 m (100 ft.). 

These results are shown in Figure 29. The green traces are results for tarmac ground conditions, 

and the orange traces are for the rFoil ground conditions. Vertical polarization results are shown 

by the solid traces, and the horizontal polarization results are shown by the dotted traces. It is 

interesting to note that the results for vertical polarization show a slight polarization inversion for 

the rFoil which is what we would expect from theory [38]. However, for the horizontal 

polarization there is no polarization inversion. The differences in magnitude are anywhere from 

0 dB to 10 dB depending on the frequency. 

(a) (b) (c)

Figure 27. Simulation of GM turntable over an asphalt dielectric medium. The dipole is in the vertical 

polarization. The results in (a) show the field uniformity above “earth”. The results in (b) show the field 

uniformity above a 5 m by 5 m “turntable”. The results in (c) are the fields looking down from the dipole over the 

ground plane.

Ground

Plane
24 

Figure 28. Photographs showing Rfoil laid out beneath aircraft for the various 

ground condition experiments. 
25 

Figure 29. Extrapolation measurements with various ground conditions. The orange traces show Rfoil results and the green traces show tarmac results. The solid traces are vertical polarization results and the dotted traces are horizontal polarization results. From left to right results are shown for distances from 15.2 m to 30.5 m.

0 500 1000 1500 2000 2500 3000

Frequency (MHz)

-20-40-60

0

Penetration (dB) DRG

(Extrap Tarmac vs. Extrap Rfoil)

15.2 m (50 ft.) - Vpol Extrap Tarmac15.2 m (50 ft.) - Hpol Extrap Tarmac15.2 m (50 ft.) - Vpol Extrap Rfoil15.2 m (50 ft.) - Hpol Extrap Rfoil

0 500 1000 1500 2000 2500 3000

Frequency (MHz)

-20-40-60

0

Penetration (dB) DRG

(Extrap Tarmac vs. Extrap Rfoil)

23.5 m (75 ft.) - Vpol Extrap Tarmac23.5 m (75 ft.) - Hpol Extrap Tarmac23.5 m (75 ft.) - Vpol Extrap Rfoil23.5 m (75 ft.) - Hpol Extrap Rfoil

0 500 1000 1500 2000 2500 3000

Frequency (MHz)

-20-40-60

0

Penetration (dB) DRG

(Extrap Tarmac vs. Extrap Rfoil)

30.5 m (100 ft.) - Vpol Extrap Tarmac30.5 m (100 ft.) - Hpol Extrap Tarmac30.5 m (100 ft.) - Vpol Extrap Rfoil30.5 m (100 ft.) - Hpol Extrap Rfoil

0 500 1000 1500 2000

Frequency (MHz)

-20-40-60

0

Penetration (dB) TEM

(Extrap Tarmac vs. Extrap Rfoil)

15.2 m (50 ft.) - Vpol Extrap Tarmac15.2 m (50 ft.) - Hpol Extrap Tarmac15.2 m (50 ft.) - Vpol Extrap Rfoil15.2 m (50 ft.) - Hpol Extrap Rfoil

0 500 1000 1500 2000

Frequency (MHz)

-20-40-60

0

Penetration (dB) TEM

(Extrap Tarmac vs. Extrap Rfoil)

23.5 m (75 ft.) - Vpol Extrap Tarmac23.5 m (75 ft.) - Hpol Extrap Tarmac23.5 m (75 ft.) - Vpol Extrap Rfoil23.5 m (75 ft.) - Hpol Extrap Rfoil

0 500 1000 1500 2000

Frequency (MHz)

-20-40-60

0

Penetration (dB) TEM

(Extrap Tarmac vs. Extrap Rfoil)

30.5 m (100 ft.) - Vpol Extrap Tarmac30.5 m (100 ft.) - Hpol Extrap Tarmac30.5 m (100 ft.) - Vpol Extrap Rfoil30.5 m (100 ft.) - Hpol Extrap Rfoil
26 

3.3 Antenna Gain 

A simulation was performed to understand how antenna gain impacts the field penetration into 

an aircraft. Using two antenna types we evaluated the shielding effectiveness. The first was a 

short dipole and the second an aperture antenna to represent a DRG horn antenna. These models 

are shown in Figure 30. Simulated reference measurements were taken for both antennas at the 

same distances, and then the receiving antennas were placed at the same position inside a 

shielded structure. The shielding effectiveness of the structure was obtained and a 200 MHz 

frequency averaging was applied to obtain an average shielding value per unit frequency. The 

theoretical gains were then computed for each antenna and the gain difference was computed. 

This was then plotted against the shielding difference of the two antenna types for the two 

shielding simulations and is shown in Figure 31. The result of the simulation shows that with 

higher antenna gains, higher shielding values can be obtained. For a reference measurement, the 

gains of both antennas are taken into account by the measurement. When the receiving antenna is 

placed inside a cavity, the gain of the cavity plus antenna changes and the gain of the receiving 

antenna must be corrected. Thus we correct for this gain in the processing of the data. This is 

considered in our uncertainty analysis. Figure 32 shows an actual set of measurements and the 

difference in penetration that can occur between applying a gain correction (black trace) and not 

applying gain correction (red trace) for a measurement on a Bombardier Global 5000 [18] with 

the receiving antenna in the main passenger cabin and the transmitting tower at the 0° position. 

Figure 30. Two antenna types used for antenna gain simulation.

Short

Dipole

Aperture Antenna

Similar to

Dual-Ridged

Horn

Figure 30. Two antenna types used for antenna gain simulation.

Short

Dipole

Aperture Antenna

Similar to

Dual-Ridged

Horn
27 

500 1000 1500 2000 2500 3000

Frequency (MHz)

0

4

8

12

16

Delta Shielding & Delta Gain (dB)

Computed Shielding Difference-200 MHz Average

Theoretical Gain Difference

Figure 31. Shielding difference plotted against the 

theoretical gain difference.

500 1000 1500 2000 2500 3000

Frequency (MHz)

0

4

8

12

16

Delta Shielding & Delta Gain (dB)

Computed Shielding Difference-200 MHz Average

Theoretical Gain Difference

Figure 31. Shielding difference plotted against the 

theoretical gain difference.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

Bombardier

DRG - Hpol

angular scan 1 - 0 position

Gain correction

No Gain Correction

Figure 32. Difference between using a gain correction and no

gain correction for a DRG horn antenna.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

Bombardier

DRG - Hpol

angular scan 1 - 0 position

Gain correction

No Gain Correction

Figure 32. Difference between using a gain correction and no

gain correction for a DRG horn antenna.
28 

4. Measurement System 

The configuration of the NIST measurement systems for these aircraft measurements is shown in 

Figures 33, 34, and 35. Figure 33 shows the equipment used on the receiving side of the system 

inside the aircraft. The transmitting side of the aircraft measurement system is shown in Figures 

34 and 35 for (a) the original system that made measurements to 3000 MHz, and (b) the 

upgraded system that made measurements up to 18 GHz, respectively. The system consists of: 

(1) a VNA, (2) two transmitting TEM horn antennas, and two DRG horn antennas configured for 

the horizontal and vertical polarizations, respectively, (3) a receiving TEM horn antenna and 

DRG antenna, (4) two coaxial microwave switches to select the polarization of the transmit 

antennas, and (5) two precision analog electro-optic links to cover both frequency bands (only 

the 11 GHz optical link was used during the first effort) and to provide an interconnection 

between the transmitting antennas outside the aircraft and the receiving antenna inside. Both 

links provide a significant improvement in performance over that of conventional microwave 

cables. The optical links exhibit low transmission losses and low noise, and do not pick up 

common-mode noise from environmental ambient signals. The optical links also improve 

dynamic range and have better immunity from electromagnetic interference. The heart of this 

system is a commercially available VNA that has been configured to acquire complex 

transmission data (S21, in-phase and quadrature signals). During the first effort, the VNA was 

limited to a maximum of 1601 points due to internal hardware limitations. During the second 

effort, the VNA was limited to a maximum of 16001 frequencies; however for both efforts, we 

developed software that extends the number of frequencies to any desired value. If we need 

more than the maximum number of points per window, then the software will subdivide a given 

frequency range into a user-selected number of either 1601 or 16001 point sub-bands. The DRG 

horn antennas operate from 1 GHz to 18 GHz and were configured by use of two bands, resulting 

in 32002 equally spaced measurement points from approximately 0.5 MHz to 18 GHz. The 

TEM horn antennas operate from 0.1 GHz to 4 GHz and were configured by use of one band, 

resulting in 6401 equally spaced measurement points from approximately 0.5 MHz to 4 GHz. A 

reduced frequency spacing is necessary to avoid problems due to aliasing. Prior to connecting 

the cables to the antennas, all channels were calibrated to remove systematic transmission effects 

due to cabling, switches, and the frequency and phase variations of the optical transmission link. 

This procedure calibrates the system with respect to the input of the transmitting and the output 

of the receiving antennas. Three NIST-developed ultra-wideband TEM horn antennas were used: 

two 1.2 m antennas on a tower located outside of the aircraft, either to transmit horizontally and 

vertically polarized fields, and a more compact 36 cm TEM horn located in a pre-selected 

aircraft compartment to detect energy coupled into the airframe. For the higher-frequency bands, 

three commercially available DRG antennas were used: two on the same transmitting tower 

located outside of the aircraft to transmit horizontally and vertically polarized fields, and a DRG 

antenna located in the same preselected aircraft compartment to detect energy coupled into the 

airframe. The frequency data were digitized and transferred to a laptop computer for subsequent 

data analysis and signal processing. 
29 

Transmitting TEM

horn antennas

Transmitting 

DRG

horn antennas

VNA

Laptop

(Side view)

6-port

microwave 

switch

Channel 1, 2

H-pol

Channel 3,4

V-pol

Precision 

microwave

cables

Optical fiber

from aircraft

(Top View)

Transmitting TEM

horn antennas

Transmitting DRG

horn antennas

Channel 

1, 2 

H-pol

Channel 3, 4

V-pol

Tower

2-way

microwave 

switch

11 GHz Optical 

link receiver

Figure 34. Transmitting side of the airframe shielding measurement system for 

measurements to 3000 MHz.

Figure 33. Airframe shielding measurement system (receiving side). The reverberant nature 

of the airframe permits the reception of both horizontally and vertically polarized signals.

11 GHz Optical 

Transmitter

18 GHz Optical 

Transmitter

Airframe

Receiving

TEM horn

antenna

Receiving

DRG horn

antenna

Optical Link to

Optical Receiver
30 

5. Measurement of Electromagnetic Airframe Penetration 

The extraction of airframe penetration characteristics requires a reference measurement without 

the shield or cavity and then a measurement with the shield or cavity placed between the two 

antennas. This two-step measurement process for an aircraft is shown in Figure 36. In the first 

step, a reference transmission measurement is performed by boresighting the transmitting and 

receiving antennas at a fixed distance. The reference measurements were performed at a location 

away from the aircraft in order to minimize reflections from the aircraft. This measurement 

quantifies the energy incident on the aircraft, and enables us to calibrate and remove the 

frequency-dependent effects of the antennas and interconnecting hardware. In the second step, 

the receiving antenna was placed in a selected aircraft compartment; the transmitting antennas 

were placed at fixed locations, external to the aircraft, and stepped-frequency transmission data 

were acquired. 

The reference and airframe data were processed by use of a sequence of filtering, Fourier 

transforms, and time gating to obtain the penetration values. The basic signal-processing 

sequence through which the data were obtained is shown in Figure 37. The raw frequency data 

were first filtered to maximize the signal-to-noise ratio and to minimize effects from the lowfrequency cut-off of our electro-optic link. Next, a tapered frequency-domain window was 

Figure 35. Transmitting side of the airframe shielding measurement system for 

measurements to 18000 MHz.

Transmitting 

DRG

horn antennas

VNA

Laptop

Transmitting TEM

horn antennas

(Side view)

2-way

microwave 

switch

Channel 1

H-pol

Channel 2

V-pol

Precision 

microwave

cables

Optical fiber

from aircraft

(Top View)

Transmitting TEM

horn antennas

Transmitting DRG

horn antennas

Channel 

1

H-pol

Channel 2

V-pol

Tower

11 GHz Optical 

link receiver

18 GHz Optical 

link receiver
31 

applied to both sets of data to reduce Gibbs ringing in subsequent processing. An inverse Fourier 

transform (IFT) was then applied to the processed data to obtain time-domain waveforms. Time 

gates were then applied to isolate the desired portions of waveforms and remove undesired 

portions. In the case of the reference, the time gate was applied to isolate the direct antenna-toantenna coupling and remove the effects of ground bounce and late-time reflections. We use this 

to reference every measurement to the attenuation seen in free space. Time gating was applied to 

the airframe data to isolate either the direct illumination, the direct propagation path between the 

two antennas, or the reverberant fields that are the reflected waves in the aircraft. Reflections 

due to ground bounce are embedded in the waveforms at this distance and therefore cannot be 

removed by time-gating. The time-gated data sets were then transformed back into the 

frequency domain, and the penetration (PE), was computed from the deconvolution: 

where S42 (gated reference) is the antenna-to-antenna coupling with environmental effects gated 

out. The signal propagates from port 4 and is transmitted to port 2. S42 (gated airframe) is the 

airframe transmission with gating applied to minimize noise. Since the reference and airframe 

measurements are typically carried out at different distances, a distance correction (DC) was 

applied: 

42

42

2 ( ) , (2) ( )

S gated airframe PE DC S gated reference  

Figure 36. Two-step airframe shielding measurement procedure 

used in the FAA’s Boeing 737-200 evaluation. 

Reference Measurement

Optical Fiber

Receiving 

antennas

Transmitting 

antennas

5 m 5 m

Transmitting 

antennas

5 m

Receiving 

antennas

Optical Fiber

22.9 m
32 

10 ( ) 20log , (3)

ref

D DC dB D

       



where D is the distance from the aperture of the transmitting antenna to the geometric center of 

the aircraft and Dref is the distance between the reference antennas. A detailed description of this 

procedure is given in [16]. Thus, our definition of penetration is based on a comparison of a 

direct antenna-to-antenna coupling and signal transmission through the airframe. The 

penetration, as we define it here, is the reciprocal of shielding (in decibels, penetration is the 

negative of shielding). We prefer to display results in terms of penetration because of a better 

graphical display and to normalize the results by our reference measurement. 

Single-aspect penetration characteristics for aircraft exhibit rapid variations with frequency, due 

to the large, complex cavity behavior of the aircraft. In order to obtain the volumetric-averaged

penetration for a compartment, the processed penetration data were frequency-averaged over a 

specified bandwidth by use of the process shown in Figure 38. Averaging the penetration data 

reduces the complex cavity variations, increases modal randomness, and highlights systematic 

coupling effects, but may mask narrowband details, depending on the amount of averaging 

applied. These effects are discussed in detail in references [16, 25, 26]. 

Figure 37. Signal-processing sequence to obtain airframe penetration.

Transmission measurement through airframe

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction

Transmission measurement through airframe

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction

Figure 37. Signal-processing sequence to obtain airframe penetration.

Transmission measurement through airframe

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction

Transmission measurement through airframe

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction

Aircraft penetration

Appropriate filter to

emphasize signal

Apply distance correction Distance correction relative

to antenna-to-antenna reference

Stepped-frequency

aircraft data Background=0 Background=0 Stepped-frequencyantenna reference

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Remove conditioning

For IFT

Apply time gate(s) to

isolate sample response

Condition data for FT

and reduce Gibbs ringing

Appropriate filter to

emphasize signal

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Frequency-domain

Kaiser-Bessel window

<0.02 dB passband ripple

>50 dB rejection

0.5 ns on/off transition

Frequency-domain convolution

Deconvolve airframe spectrum

with

reference spectrum Frequency-domain

antenna correction
33 

5.1 Reference Measurements

The test setup for the reference measurements is shown in Figure 39. The transmitting antennas 

are shown mounted on one tower with aperture centers located 4 m above the ground. The 

receiving antennas were mounted on a second tower. The towers were constructed from PVC 

pipes and plywood platforms to produce a low-density support structure with minimal scattering. 

The antennas were then boresighted and a distance extrapolation was performed to determine an 

optimal reference distance to minimize near-field effects and maximize the period between the 

signal and ground bounce. We performed multiple reference measurements with antenna-toantenna separations ranging from 2 m to 35 m. We found that a separation of 6 m was optimal in 

terms of accuracy and time separation. Two transmission measurements were performed namely, 

one each for the vertical and horizontal channels. This process required a manual reorientation 

of the receiving antenna to be co-polarized with each of the transmitting antennas. Once the 

reference data were taken, the receiving antenna was dismounted from the support tower and 

placed at selected locations inside the aircraft. The external antenna tower and aircraft are shown 

in Figure 40. The reference waveforms for the DRG antenna are shown in Figures 41, 42, and 

43. The reference waveforms for the TEM horn antenna are shown in Figures 42, 43, and 44. 

The ungated time-domain reference waveforms are shown in Figures 41 and 44. The doublets 

that occur at approximately 50 ns in Figure 41 and 60 ns in Figure 44 correspond to direct 

antenna-to-antenna coupling. The subsequent waveform activity was due to a combination of 

internal antenna reflections and environmental scattering due to ground bounce and reflections 

from nearby objects. Figures 42 and 45 show the ungated frequency-domain responses for the 

DRG and TEM horn references, respectively. The noise-like hash on the waveform is due to 

ground bounce and spurious reflections which were time-gated out of the reference 

measurement. The frequency-domain transmission amplitude spectra of Figures 43 and 46 show 

Processed

penetration data

PE (f

i

)

Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Frequency-averaged

penetration

( ) PE fi

Processed

penetration data

PE (f

i

)

Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Frequency-averaged

penetration

( ) PE fi

Frequency-averaged

penetration

( ) PE fi

Figure 38. The frequency-averaging definition. 

Processed

penetration data

PE (f

i

)

Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Frequency-averaged

penetration

( ) PE fi

Processed

penetration data

PE (f

i

)

Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Perform averaging

over a selected

bandwidth (BW)

1

1 ( )

N

i

i

PE f N 



Frequency-averaged

penetration

( ) PE fi

Frequency-averaged

penetration

( ) PE fi

Figure 38. The frequency-averaging definition. 
34 

the impact of applying this time gate, thus isolating direct antenna-to-antenna coupling and 

yielding the reference for penetration measurements. 

Figure 39. Reference measurement setup. The transmitting tower is configured for all 

measurements, and the receiving tower is configured for reference measurements only.

Figure 40. The transmitting antennas placed on top of a support tower and

boresighted at the center of the aircraft.

Tower
35 

20 40 60 80 100

Time (ns)

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

S21 Normalized Signal Amplitude

Antenna-to-antenna response

Ground bounce &

 spurious reflections

Figure 41. Ungated time-domain transmission waveform for a DRG 

antenna obtained at a separation of 6 m and horizontal polarization. 

0 1000 2000 3000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Figure 42. Ungated frequency-domain amplitude spectrum for a DRG horn 

antenna obtained at a separation of 6 m and vertical polarization. Note the hashy

behavior due to the spurious reflections shown in Figure 41.
36 

0 1000 2000 3000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Figure 43. Gated frequency-domain amplitude spectrum for the DRG 

horn antenna corresponding to the waveform of Figure 41.

Figure 44. Ungated time-domain transmission waveform for a 

TEM antenna obtained at a separation of 6.0 m and vertical 

polarization. 

40 60 80 100

Time (ns)

-0.08

-0.04

0

0.04

0.08

S21 Normalized Signal Amplitude

Antenna-to-antenna response

Ground bounce & 

 spurious reflections
37 

0 1000 2000 3000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Figure 45. Ungated frequency-domain amplitude 

spectrum for a TEM horn antenna obtained at a 

separation of 6.0 m and vertical polarization. Note the 

scalloping due to the large ground-bounce reflection 

shown in Figure 44.

0 1000 2000 3000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Figure 45. Ungated frequency-domain amplitude 

spectrum for a TEM horn antenna obtained at a 

separation of 6.0 m and vertical polarization. Note the 

scalloping due to the large ground-bounce reflection 

shown in Figure 44.

0 1000 2000 3000

Frequency (MHz)

-120

-100

-80

-60

-40

-20

0

S21 Magnitude (dB)

Figure 46. Gated frequency-domain amplitude spectrum for the TEM 

horn antenna corresponding to the waveform of Figure 44.
38 

6. Airframe Penetration Measurements ― Overview 

We began by measuring the penetration at several extrapolation points on the 45° line, as shown 

by the black X’s in Figure 46. These measurements are completed for every effort to ensure the 

system is performing correctly and to determine that the reference antenna separations are in the 

far-field. The data for both measurement efforts will be presented in this section; therefore some 

data will be shown for an upper frequency of 3 GHz, and other data are shown for an upper 

frequency of 18 GHz. The following measurements were performed over the course of both 

measurement efforts: (1) the transmitting antenna was placed along the 45° extrapolation line at 

the 23.5 m (75 ft.) distance, then the receiving antenna was placed in the front galley, the rear 

galley, the flight deck, and the mid-passenger cabin; (2) the receiving antenna was placed in the 

mid-passenger cabin, and the transmitting antenna was moved around the aircraft to the 0°, 90°, 

135°, and 180° positions. At the 90° position the transmitting antenna was moved in a small 

circle around this position to look at antenna pattern effects; (3) sector measurements were 

performed with the receiving antenna in the mid-passenger cabin and the transmitting antenna 

moved to the 90°, 100°, 110°, 120°, 125°, 130°, 135°, 140°, 145°, 150°, 160°, 170°, and 180° 

positions; and (4) internal propagation between cavities were measured. The transmitting 

antenna was placed in the mid-passenger cabin and the receiving antenna was placed in the flight 

deck, the main cabin, the cargo bay, and the avionics bay. The transmitting antenna was then 

moved to the cargo bay and the receiving antenna was located in the avionics bay. Each of these 

positions is shown by the red X’s in Figure 44. Where applicable, we applied antenna gain and 

distance correction factors to maintain consistency in the results. 

Figure 47. Test master graphic showing internal measurement positions (red X’s), 

Extrapolation distances (black X’s), measurements around aircraft (blue, dashed 

line) at a distance of 23 m (75 ft). 

0

30

60

90

120

150

180

210

240

270

300

330

20

30

40

50

75

100
39 

6.1 Extrapolation Results 

We performed a set of extrapolation measurements from 6.1 m (20 ft) to 30.5 m (100 ft). The 

transmitting antennas were moved along the 45° line and the receiving antennas were located in 

the main cabin. These measurements were used to determine whether we were in the far-field 

and to understand how penetration changes as a function of distance from the aircraft. Distance 

correction was applied to the data by use of a reference distance of 6.1 m. These data are shown 

in Figures 48 to 51. These measurements show a spread in the data of about 7 dB to 10 dB 

across the frequency spectrum for the DRG antennas and around 10 dB for the TEM horn 

antennas. The large spread in the data is due mostly to the 6.1 m distance for the DRG antennas 

and the 6.1 m, 9.1 m and 30.5 m distances for the TEM horn antennas. If we remove these data 

sets, we tighten up the spread to between 3 dB and 6 dB for both sets of antennas. We believe 

this is because, at the closer distances, our antennas see only a spot size of the aircraft, but as we 

move further from the aircraft the antennas see more of the aircraft and the surrounding 

environment. The DRG antennas have higher directivity than the TEM horn antennas, which 

corresponds to the greater spread in penetration data for the TEM horn antennas. These results 

have been both corrected for distance and for antenna gain. A discussion of the gain for the 

DRG horn antenna and TEM horn antenna is given in Appendix A. 

0 500 1000 1500 2000 2500 3000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

DRG - Hpol

6.1 m (20 ft.)

9.1 m (30 ft.)

12.1 m (40 ft.)

15.2 m (50 ft.)

23.5 m (75 ft.)

30.5 m (100 ft.)

Figure 48. Extrapolation measurements for the DRG antenna, 

horizontal polarization.
40 

0 500 1000 1500 2000 2500 3000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

DRG - Vpol

6.1 m (20 ft.)

9.1 m (30 ft.)

12.1 m (40 ft.)

15.2 m (50 ft.)

23.5 m (75 ft.)

30.5 m (100 ft.)

Figure 49. Extrapolation measurements for the DRG 

antenna, vertical polarization.

0 500 1000 1500 2000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

TEM - Hpol

6.1 m (20 ft.)

9.1 m (30 ft.)

12.1 m (40 ft.)

15.2 m (50 ft.)

23.5 m (75 ft.)

30.5 m (100 ft.)

Figure 50. Extrapolation measurements for the 

TEM antenna, horizontal polarization.
41 

6.2 Penetration into aircraft from 45° extrapolation line 

These measurements were used to study penetration as a function of the receiving antenna’s 

internal position. To accomplish this, the receiving antenna was moved to several locations 

within the aircraft. Internal receiving antennas were located in the flight deck, the front and rear 

galleys, and the mid-passenger cabin. The transmitting antenna was located on the 45° 

extrapolation line at 23.5 m (75 ft.). This location was chosen because we had performed more 

than one measurement at this position. At some positions, more than one measurement was 

taken. 

6.2.1 Measurements in the Flight Deck 

Figure 52 shows the placement of the receiving antennas for measurements taken at position 4 in 

the flight deck (see Figure 53). The TEM horn antenna was placed on the pilot’s seat facing the 

outside of the aircraft. The DRG horn antenna was placed on the co-pilot’s seat facing the 

instrument panel. Results at this position are shown in Figure 53. The graph shows that 

horizontally polarized fields allow greater penetration into the flight deck than vertically 

polarized fields. The TEM results are shown at the lower frequencies (red and light blue traces) 

and the DRG results are shown at the higher frequencies (orange and dark blue traces). The 

horizontally polarized TEM horn antenna results show penetration values on the order of −15 dB 

and the vertically polarized TEM horn antenna shows an average penetration around −22 dB. 

The horizontally polarized DRG horn antenna results show penetration values of approximately 

−15 dB, at around 4000 MHz with a constant decay up to 18,000 MHz, where values are 

approximately −30 dB. The vertically polarized DRG horn antenna starts with a penetration of 

0 500 1000 1500 2000

Frequency (MHz)

-60

-40

-20

0

Penetration (dB)

TEM - Vpol

6.1 m (20 ft.)

9.1 m (30 ft.)

12.1 m (40 ft.)

15.2 m (50 ft.)

23.5 m (75 ft.)

30.5 m (100 ft.)

Figure 51. Extrapolation measurements for the 

TEM antenna, vertical polarization.
42 

around −20 dB at 2000 MHz, has a sharp drop from 3000 MHz to 4000 MHz, and then has a 

fairly constant value of −35 dB across the rest of the frequency band, with values ranging from 

−30 dB to −40 dB, depending on the frequency. 

The placement of the receiving antennas for measurements taken at position 5 (see Figure 55) in 

the flight deck, is shown in Figure 54. The TEM horn antenna was in the pilot’s seat pointing 

upward toward the flight deck windows. The DRG horn antenna was in the co-pilot’s seat 

pointing toward the ceiling of the flight deck. Results at this position are shown in Figure 55. 

The graph shows that horizontally polarized fields allow greater penetration into the flight deck 

than vertically polarized fields. The horizontally polarized TEM horn antenna results show 

penetration values on the order of −10 dB at around 1000 MHz, and for the vertically polarized 

TEM horn antenna penetration shows a peak value at around −12 dB at 1000 MHz. The 

horizontally polarized DRG horn antenna penetration values rise from −20 dB to −15 dB from 

1000 MHz to 2000 MHz and then have a constant decay up to 18,000 MHz, where we show 

values around −30 dB. The vertically polarized DRG horn antenna values start with a 

penetration of around −15 dB at 2000 MHz, drops from −15 dB to −35 dB from 2000 MHz to 

6000 MHz and then has an average value around −30 dB across the rest of the frequency band, 

with values ranging from −20 dB to −40 dB, depending on the frequency. 

Figure 52. Placement of receiving DRG and TEM horn antennas in the flight deck for position 4.
43 

Figure 53. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

the 45° extrapolation line and the receiving antennas placed in the flight deck. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (

dB)

Flight Deck - 45 degrees

position 4

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

Figure 54. Placement of receiving DRG and TEM horn antennas in the flight deck for position 5.
44 

6.2.2 Measurements in the Front Galley 

The placement of the receiving antennas for measurements taken at position 3 (see Figure 57) in 

the front galley is shown in Figure 56. The TEM horn antenna is shown pointing toward the 

cabin door. The DRG horn antenna is shown pointing toward the galley closet on the opposite 

side of the aisle. Results for this position are shown in Figure 57. The horizontally polarized 

fields penetrate into the aircraft better than the vertically polarized fields. The horizontally 

polarized TEM horn antenna peaks at a penetration value of −15 dB between 1000 MHz and 

2000 MHz, and the vertically polarized TEM horn antennas peaks at a value of −18 dB between 

1000 MHz and 2000 MHz. The horizontally polarized DRG horn antenna penetration values 

begin at −15 dB between 3000 MHz and 4000 MHz and drop to a value of approximately 

−28 dB at 18,000 MHz. Penetration values for the vertically polarized DRG horn antenna begin 

at a value of approximately −22 dB at 2000 MHz and drop to a value of −38 dB at 18,000 MHz. 

These values are slightly higher than for the flight deck. This could be due to the contribution 

from the windows in the mid-passenger cabin.

Figure 55. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed 

along the 45° extrapolation line and the receiving antennas placed in the flight deck. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Flight Deck - 45 degrees

position 5

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330
45 

Figure 56. Placement of receiving DRG and TEM horn antennas in the front galley for position 3.

Figure 57. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the front galley for position 3. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Front Galley - 45 degrees

position 3

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

75
46 

6.2.3 Measurements in the Rear Galley 

The antennas were then moved to the rear galley and two sets of measurements were taken. The 

placement of the receiving antennas, for measurements taken at position 6 (see Figure 59) in the 

rear galley, is shown in Figure 58. The TEM horn antenna is shown pointing upward into the 

corner between the ceiling and the rear cabin door. The DRG antenna is shown pointing toward 

the corner between the bathroom area and the rear cabin door on the opposite side of the aisle. 

Results for this position are shown in Figure 59. The difference in penetration between the 

horizontally polarized fields and the vertically polarized fields is not as pronounced as in the 

previous measurements and are on the order of a few decibels at certain frequencies. The 

horizontally polarized TEM horn antenna penetration values begin at a value around −30 dB at 

approximately 100 MHz and peak at a value of −20 dB at around 1000 MHz. The vertically 

polarized TEM horn antenna penetration values begin at values around −35 dB at 100 MHz and 

peak at a value of about −22 dB at 1000 MHz. The horizontally polarized DRG horn antenna 

penetration values begin at a value of −23 dB at 1000 MHz, rise to a value of −20 dB at 

4000 MHz, and then drop to a value of around −28 dB at 18,000 MHz. The vertically polarized 

DRG horn antenna penetration values begin at a value of approximately −22 dB at 1000 MHz, 

rise to a value of approximately −21 dB at 2000 MHz, and drop to a value of −30 dB at 

18,000 MHz. The variation in penetration values is less dramatic than for the previous positions. 

For measurements taken at position 7 (see Figure 61) in the rear galley, the receiving antennas 

were placed as shown in Figure 60. The TEM horn antenna is shown pointing upward toward 

the ceiling and toward the front of the aircraft. The DRG antenna is shown pointing almost 

directly toward the front of the aircraft in the horizontal polarization, but on the opposite side of 

the aisle. Results for this position are shown in Figure 61. The difference in penetration 

between the horizontally polarized fields and the vertically polarized fields is now increased to 

around 5 dB to 10 dB as the frequency increases. The horizontally polarized fields have greater 

penetration. The horizontally polarized TEM horn antenna penetration values begin at a value 

around −30 dB at approximately 100 MHz and peak at a value of −20 dB at around 1500 MHz. 

The vertically polarized TEM horn antenna penetration values begin at values around −35 dB at 

100 MHz and peak at a value −25 dB at 1000 MHz. The horizontally polarized DRG horn 

antenna penetration values begin at a value of −20 dB at 1000 MHz, show values from −20 dB to 

−25 dB between 2000 MHz and 14000 MHz, and then vary from −20 dB to −25 dB from 

15,000 MHz to 18,000 MHz. The vertically polarized DRG horn antenna peaks at a value of 

approximately −20 dB at 2000 MHz, varies from −23 dB to −30 dB from 2000 MHz to 

12,000 MHz and averages to a penetration value of −30 dB from 12,000 MHz to 18,000 MHz. 

A distance correction is applied when the reference measurement distance and the shielding 

measurement distance are different, as discussed at the beginning of Section 5. Common sense 

would lead us to process the data using the actual geometric distance between antennas; 

however, in this type of an environment, this approach does not work because the actual flight 

path is not known, due to multiple apertures. Typically, we use the geometric center of the 

aircraft for distance corrections so that results can be compared. Another possibility is to 

observe the onset of the signal in the time-domain and use this value (converted to distance) to 

distance-correct the data. For this set of measurements in the rear galley, we applied a distance 

correction of 29.3 m (96 ft.). Results for position 6 are shown in Figure 62, and results for 
47 

position 7 are shown in Figure 63. This experiment shows that penetration values can vary by 

about 2 dB, depending on the distance correction that is used. The difference in distance 

between the time-domain signal onset and the 23.5 m (75 ft.) is approximately 6 m. For 

consistency between this technical note and previous technical notes, a 23.5 m (75 ft.) distance 

correction has been used. The time-of-flight distance correction has not been used but could be a 

topic of discussion for future measurements.

Figure 58. Placement of receiving DRG and TEM horn antennas in the rear galley for position 6.
48 

Figure 60. Placement of receiving DRG and TEM horn antennas in the rear galley for position 7.

Figure 59. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed 

along the 45° extrapolation line and the receiving antennas placed in the rear galley at position 6. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Rear Galley - 45 degrees

position 6

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

75
49 

Figure 62. Results showing penetration difference

due to distance correction factor for rear galley data.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-40

-35

-30

-25

-20

Penetration (dB)

DRG-V

Rear Galley to 23.5 m (75ft.)

45 deg extrap_pos 6

Distance corrected to 23.5 m (75ft.)

Distance corrected to 29.3 m (96 ft.)

 (Time-domain distance)

Figure 62. Results showing penetration difference

due to distance correction factor for rear galley data.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-40

-35

-30

-25

-20

Penetration (dB)

DRG-V

Rear Galley to 23.5 m (75ft.)

45 deg extrap_pos 6

Distance corrected to 23.5 m (75ft.)

Distance corrected to 29.3 m (96 ft.)

 (Time-domain distance)

Figure 61. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed 

along the 45° extrapolation line and the receiving antennas placed in the rear galley at position 7. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Rear Galley - 45 degrees

position 7

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

75
50 

6.2.4 Measurements in the Mid-Passenger Cabin 

The final location for the extrapolation-line measurements was in the mid-passenger cabin. Two 

sets of measurements were completed here. The placement of the receiving antennas, for 

measurements taken at position 2 (see Figure 65) in the mid-passenger cabin, is shown in Figure 

64. Both antennas were pointing toward the ceiling and were positioned at approximately the 

same angles. Results for this position are shown in Figure 65. The horizontally polarized fields 

have greater penetration than the vertically polarized fields. The horizontal polarized TEM horn 

antenna penetration values begin at a value around −20 dB at approximately 100 MHz and peak 

at a value of −10 dB at around 1000 MHz. The vertically polarized TEM horn antenna 

penetration values begin at values around −25 dB at 100 MHz and peak at a value of −25 dB at 

1000 MHz. The horizontally polarized DRG horn antenna penetration values begin at a value of 

−10 dB at 1000 MHz and vary from −10 dB at 2000 MHz to −15 dB at 18,000 MHz. The 

vertically polarized DRG horn antenna peaks at a penetration value of approximately −15 dB at 

2000 MHz and varies from −15 dB to −30 dB from 2000 MHz to 18,000 MHz. 

Figure 63. Results showing penetration difference

due to distance correction factor for rear galley data.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-40

-35

-30

-25

-20

Penetration (dB)

DRG-V

Rear Galley to 23.5 m (75 ft.)

45 deg extrap_pos 7

Distance corrected to 23.5 m (75ft.)

Distance corrected to 29.3 m (96 ft.)

 (Time domain distance)

Figure 63. Results showing penetration difference

due to distance correction factor for rear galley data.

0 4000 8000 12000 16000 20000

Frequency (MHz)

-40

-35

-30

-25

-20

Penetration (dB)

DRG-V

Rear Galley to 23.5 m (75 ft.)

45 deg extrap_pos 7

Distance corrected to 23.5 m (75ft.)

Distance corrected to 29.3 m (96 ft.)

 (Time domain distance)
51 

For the second set of data the antennas remained in the same location, but both receiving 

antennas were positioned to point into the floor of the main passenger cabin. Beneath the main 

passenger cabin floor is the cargo bay. This is position 3 (see Figure 67) as shown in Figure 66, 

and results for this position are shown in Figure 67. Again, the horizontally polarized fields have 

greater penetration than the vertically polarized fields and this penetration is most likely due to 

the main cabin windows. The horizontally polarized TEM horn antenna penetration values begin 

around −20 dB at approximately 100 MHz and peaks at a value of −10 dB at around 1000 MHz. 

The vertically polarized TEM horn antenna penetration values begin around −25 dB at 100 MHz 

and peak at a value of −15 dB at 1000 MHz. The horizontally polarized DRG horn antenna 

penetration begins at a value of −10 dB at 1000 MHz and varies slowly down to a value of 

−20 dB at 18,000 MHz. The vertically polarized DRG horn antenna penetration peaks at a value 

of approximately −15 dB at 1500 MHz and drops to −35 dB at 8000 MHz and then varies at 

values from −30 dB to −35 dB from 8000 MHz to 18,000 MHz. 

Figure 64. Placement of receiving DRG and TEM horn antennas in the mid-passenger cabin for 

position 2.
52 

Figure 65. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed

along the 45° extrapolation line and the receiving antennas placed in the mid-passenger cabin at position 2

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Passenger - 45 degrees

position 2

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

75

Figure 66. Placement of receiving DRG and TEM horn antennas in the mid-passenger cabin for 

position 3.
53 

6.3 Mid-Passenger Cabin Penetration Results 

For the next series of measurements, the receiving TEM and DRG antennas were placed in the 

mid-passenger cabin and were positioned as shown in Figures 68 and 69. The setup is the same 

in both photos, but a photograph was taken from the front of the antennas and from behind the 

antennas to show their proximity to the front and rear of the aircraft. 

6.3.1 Single-Position Quadrant Measurements 

Four transmitting locations were measured with the receiving antennas at the same location and 

in the same orientation for all four measurements in the mid-passenger cabin. The transmitting 

antennas were located at the 23.5 m (75 ft.) radius at the 0° position, the 90° position, the 135° 

position and the 180° position, as shown by the red X’s in Figure 70. We again notice that the 

horizontally polarized fields tend to penetrate more easily into the aircraft than do the vertically 

polarized fields, although the differences are not as large as in some of the previous 

measurements. At the 0° position, for the transmitting antennas in the horizontal polarization, 

the penetration values vary from −25 dB at 100 MHz to a peak value of −17 dB at around 

2000 MHz. The penetration also varies from −20 dB to −30 dB from 2000 MHz to 18,000 MHz. 

For the transmitting antennas in the the vertical polarization, the penetration values vary from 

−25 dB to −30 dB across the frequency spectrum. At the 90° position, the vertical and horizontal 

polarization results lie almost directly on top of each other. Penetration values rise to a peak 

value of −10 dB around 2000 MHz down to −20 dB at 18,000 MHz. We measured 

approximately the same behavior for the 135° position. At the 180° position the horizontally 

Figure 67. Penetration versus frequency for all antennas and polarizations for the transmitting tower placed 

along the 45° extrapolation line and the receiving antennas placed in the mid-passenger cabin at position 3. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Passenger - 45 degrees

position 3

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

75
54 

polarized fields penetrate more easily at the lower frequencies up to about 12,000 MHz, and then 

the values are only slightly above those of the vertically polarized fields. The highest penetration 

occurs for the horizontally polarized fields from 500 MHz to 1000 MHz at a value of −20 dB; it 

then drops to a value of −35 dB at 12,000 MHz, and is constant at a value of −35 dB from 

12,000 MHz to 18,000 MHz. The maximum penetration for the vertically polarized fields occurs 

at around 2000 MHz at a value of −30 dB;p it then drops to a value of −40 dB between 

8000 MHz and 12,000 MHz and then increases to a value of −35 dB at 18,000 MHz. We moved 

the tower approximately 0.3 m to the left and then took another set of measurements and notice 

that the results are virtually the same as those from the 180° position. We see maximum 

penetration into this aircraft at the measured angles of 90° and 135°. The minimum penetration 

occurs at the 180° position, and the penetration through the flight deck shows results between 

these two extremes. 

At the 90° position, from the previous set of measurements, we took a tight circular sweep 

around this position to look at results and how they depend on the antenna pattern of both the 

DRG horn antennas and the TEM horn antennas. While at the 90° position, we initially 

boresighted the antenna at the midsection of the aircraft. We then moved the transmitting 

antenna tower 45° degrees to the left and took another measurement; we then moved the tower 

another 45° at this same 90° clock position to a 90° offset from boresight and then again with the 

antennas facing 180° from boresight of the aircraft. The results of these measurements are 

shown in Figure 68. With the antenna boresighted at the aircraft, the vertically polarized and 

horizontally polarized penetration values lie almost directly on top of each other. They rise to a 

peak value of −10 dB at around 2000 MHz, and down to −20 dB at 18,000 MHz. This 

measurement taken at 90o is the same as in the previous section 6.3.1. With the antenna pointing 

45° to the left of the boresight position (pointing at the tail) we obtain the results shown in Figure 

71. We immediately see two results: the first is the band-edge discontinuity between the results 

of the vertically polarized TEM horn antenna and the DRG horn antenna. The second is the 

large spike in the vertically polarized data that occurs at approximately 17,000 MHz. We can 

speculate that this might be an ambient signal picked up only with the antennas in the vertical 

polarization. At the 90o offset, we see dominant influences for vertically polarized antennas. 

There is a band-edge discontinuity between the results for the TEM horn antennas and the DRG 

horn antennas, and then a large signal drop in the 8000 MHz to 10,000 MHz frequency band. 

Finally, as the antennas are pointed 180° away from the aircraft, we see a large discontinuity 

between the horizontally and vertically polarized TEM horn antenna low-frequency band and the 

horizontally and vertically polarized DRG horn antenna high-frequency band. This is most 

likely due to small signal levels from the back-lobes of the antennas. 
55 

Figure 68. Placement of receiving DRG and TEM horn antennas in the 

mid-passenger cabin for single-position quadrant measurements looking 

toward front of aircraft.

Figure 69. Placement of receiving DRG and TEM horn antennas in the 

mid-passenger cabin for single-position quadrant measurements looking 

toward rear of aircraft.
56 

6.3.2 Rear Quadrant Sector Measurements 

The receiving antennas remained in the same position as for the previous set of measurements. 

The transmitting antenna tower was moved to positions around the rear quadrant of the aircraft 

from 90o to 180o. Measurements were taken every 10o from 90o to 120o and from 150o to 180o 

and then every 5o from 120o to 150o. These tests were designed to give us information on how 

many positions around the aircraft are required to fully characterize the penetration [29]. Further 

information is given in Appendix B. Based on a theoretical analysis for a single cut-plane, the 

number of positions required to fully characterize the Bombardier Global 5000 at 1 GHz is 1197, 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

(move 1 ft)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 0 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 135 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

20

0 4000 8000 12000 16000 2

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (pointed at midsection)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

(move 1 ft)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 0 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 135 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

20

0 4000 8000 12000 16000 2

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (pointed at midsection)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

Figure 70. Penetration versus frequency for all antennas and polarizations for the 

transmitting tower moved around the aircraft at single positions in each quadrant. The 

receiving antenna is in the mid-passenger cabin. 
57 

at 5 GHz it is 5973, and at 18 GHz, the number of positions required to fully characterize the 

aircraft increases to 21505 [31]. This is based on the equation 

N ka for ka 4 2 1, (4) c  

where k is the propagation constant k  2 /   , and a is the radius of the object. For the 

Bombardier Global 5000, we used the largest dimension for the radius, which would be the 

length of the aircraft. Since the number of positions required to fully characterize the aircraft are 

impractical to implement for testing, we wanted to know whether any major penetration points 

would be missed, and thus we decided to sample at the positions given above. 

The results for angular positions from 90o to 130o are shown in Figure 72. For the measurements 

in general, we see that the horizontally polarized TEM horn antenna shows penetration values 

that are lower than those for the vertically polarized TEM horn antenna. Also, there seems to be 

a resonance that occurs at around 400 MHz for the horizontally polarized fields; we have seen 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (45 degrees ptd away from 737)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (90 degrees offset)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (180 degrees offset)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 4000 8000 12000 16000 20000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (pointed at midsection)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0

30

60

90

120

150

180

210

240

270

300

330

20

Pointed at

midsection

45 degree

offset 90 degree

offset

180 degree

offset

Figure 71. Penetration versus frequency for all antennas and polarizations for the transmitting tower 

moved in a small circle at the 90° position. The receiving antenna is in the mid-passenger cabin. 
58 

this in several other aircraft types. For the measurement at 90o, we see that at the higher 

frequencies the traces for horizontally and vertically polarized antennas lie almost directly on top 

of one another. There is a discontinuity between band edges at around 1 GHz that could have 

something to do with antenna alignment, as discussed in the previous section. Penetration values 

appear to average out around −20 dB across this bandwidth. Because these measurements were 

taken at a later date than results shown in the previous measurements and with a different 

system, we would expect the measurements to be the same only to within a specified uncertainty. 

These uncertainties will be addressed at the end of this technical report. However, for 

comparison, we introduce the measurement results from the previous section (6.3.1) into Figure 

73. The plot on the left shows measurement results from October 2004, which are the same 

results shown in Figure 72. The average value is about −20 dB across the frequency bandwidth. 

The plot on the right shows the measurement results from October 2005, which shows that the 

average value varies from −10 dB to −15 dB. Although these two results are different, we have 

to remember that repeatability is a function of both the transmitting location on the outside of the 

aircraft and the receiving location on the inside of the aircraft and the orientation of the receiving 

or transmitting antennas. At the 100o position, we see a 1 dB to 2 dB difference at the band 

edges and the penetration value seems to average around −22 dB across this bandwidth of 

interest. For the 90o, 100o and 110o positions, there appears to be a slight peaking of values from 

approximately 500 MHz to 1000 MHz for the vertically polarized antennas. At the 110o 

position, the penetration values for the horizontally and vertically polarized antennas tend to 

overlap in the higher frequency band with an approximate average of −22 dB. For the angular 

positions from 120o to 130o, the penetration values average out to around −20 dB and the 

differences between the values for horizontally polarized and vertically polarized antennas are 

minimal. 

Figure 74 shows the penetration results for angular positions from 135o to 180o. Again, in these 

plots we see a resonance that occurs at around 400 MHz for the horizontally polarized TEM horn 

antenna. Band edges tend to align to within 1 dB to 2 dB, and there is not much difference 

between the horizontally and vertically polarized antennas until we reach 160o to 180o. The 

average penetration value for 135o and 140o is around −20 dB to −22 dB. At 145o the average 

penetration value has dropped to around −22 dB, and at 150o the average penetration value has 

dropped to around −25 dB. For the 160o angular position, frequencies below 1000 MHz show 

the same penetration values of around −30 dB, but above 1000 MHz, the horizontally polarized 

antenna shows an average penetration value of approximately −25 dB and the vertically 

polarized antenna shows an average penetration value of approximately −28 dB. At 170o the two 

different polarizations split further, with results for the horizontally polarized antenna 

maintaining an average penetration value of −25 dB, and those for the vertically polarized 

antenna having an average penetration value around −35 dB. At the 180o position, the two 

polarizations have greater differences in the high-frequency band and are now at approximately 

−30 dB and −40 dB in the horizontal polarization and vertical polarization, respectively. For the 

lower frequency band, these results compare to within 5 dB of those shown in Figure 75, and to 

within 5 dB to 7 dB in the upper frequency band. 
59 

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 90 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 120 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 100 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 110 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 125 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 130 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

Figure 72. Penetration versus frequency for all antennas and polarizations for the transmitting tower moved to angular positions, 90°, 100°, 110°, 120°, 125°, and 130°. The receiving antenna is in the mid-passenger cabin. 
60 

Figure 73. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 90° position. The 

tests on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were 

taken with a system having a bandwidth of 18,000 MHz.

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (pointed at midsection)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Main Cabin - 90 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

Figure 73. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 90° position. The 

tests on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were 

taken with a system having a bandwidth of 18,000 MHz.

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 90 degrees

 (pointed at midsection)

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Main Cabin - 90 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol
61 

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB) Main Cabin - 135 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 150 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 180 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 170 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 140 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 145 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-10-20-30-40-50

0

Penetration (dB)

Main Cabin - 160 degrees

TEM - Hpol

DRG - HpolTEM - VpolDRG - Vpol

Figure 74. Penetration versus frequency for all antennas and polarizations for the transmitting tower moved to angular positions, 135°, 140°, 145°, 

150°, 160°, and 170°, 180°. The receiving antenna is in the mid-passenger cabin.
62 

Figure 75. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 180° position. The tests 

on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were taken with a 

system having a bandwidth of 18,000 MHz.

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Main Cabin - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

Figure 75. Comparison between Oct 2004 tests (left) and October 2005 tests (right) at the 180° position. The tests 

on the left were taken with a system having a bandwidth of 6000 MHz and the tests on the right were taken with a 

system having a bandwidth of 18,000 MHz.

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Mid Section - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol

0 1000 2000 3000

Frequency (MHz)

-50

-40

-30

-20

-10

0

Penetration (dB)

Main Cabin - 180 degrees

TEM - Hpol

DRG - Hpol

TEM - Vpol

DRG - Vpol
63 

6.4 Intercompartmental Insertion Loss Measurements 

Aircraft manufacturers are concerned with high-level RF signals entering aircraft compartments 

where flight-sensitive equipment is installed. They will typically measure the penetration of 

high-level fields into these compartments where aircraft control systems exist. Usually, the 

receiving antenna is placed into the cavity along with a small stirrer and then the reverberant 

fields are measured to obtain a time and spatial average of the fields over the volume of the 

cavity. Because aircraft testing is time-consuming and expensive, typically only a few positions 

are measured, and the cavity is assumed to exhibit reverberant behavior. If the cavity is assumed 

to be reverberant, then statistically the electric field is uniform over the volume of that cavity. 

To verify this assumption, NIST decided to measure the insertion loss between aircraft cavities 

for several different positions without the use of mode-stirring/mode-tuning. The results are 

presented here. We have also included more information on statistics for the Bombardier Global 

5000 and the Premier IA in Appendix C and numerical simulations for interior propagation 

measurements for the 737-200 in Appendix D. 

6.4.1 Main Cabin to Main Cabin 

The DRG and TEM horn antennas were measured at various positions around the main cabin. 

The DRG antenna positions were not measured at the same time as the TEM horn antenna 

positions because only two channels were available from the VNA at any one time for the 

internal configurations. In general, for each compartment-to-compartment measurement we tried 

to position them in approximately the same position for each of these runs. 

6.4.1.1 Combined TEM horn antenna positions 

Six positions were measured by use of the TEM horn antennas. For setup 1, the measurement 

was taken twice without repositioning antennas with the main cabin door open and closed. 

Figure 76 shows all measurement results in the main cabin for the TEM horn antenna showing a 

maximum insertion loss of around −35 dB and a minimum insertion loss of around −75 dB. 

Figures 77 shows the results for the measurement having maximum cabin insertion loss, 

minimum insertion loss and two system noise-floor measurements. The first noise-floor 

measurement was taken with the aircraft’s Auxiliary Power Unit (APU) on and the second was 

taken with the APU off. 

Whisker-box plots are shown in Figure 78 for the following center frequencies, (1) 100 MHz, (2) 

500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these plots 

are from a 200 MHz bandwidth around each center frequency. These plots show that the median 

insertion loss for these frequencies have values from about −45 dB to −85 dB. The maximum 

insertion loss for these frequencies is approximately −30 dB in a 200 MHz bandwidth around a 

center frequency of 1500 MHz, and the minimum insertion loss is −118 dB in a 200 MHz 

bandwidth around a center frequency of 100 MHz. Fifty percent of the data occurs in the light 

blue and dark blue boxes in the 25th and 75th percent quartiles. The program used to process this 

data does not give the distribution of points in the upper and lower tails of this data. 
64 

In reverberation chambers, common statistical distributions used to evaluate the cavity are the 

chi-squared probability density function (χ

2

 pdf) and the chi-squared cumulative distribution 

function (χ

2

 cdf). The χ

2

 pdf for all TEM horn antenna measurements is shown in Figure 79 and 

the χ

2

 cdf for all TEM horn antenna measurements is shown in Figure 80. The histogram in 

Figure 79 consists of all points binned into 1 dB bins (light-blue bins) and plotted against the 

theoretical probability density function (dark-blue trace) and the average value of the theoretical 

data (pink trace). The theoretical average value is around −38 dB. Figure 80 is the data (dark0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Main Cabin 

TEM - Setup 1 (door open)

TEM - Setup 1

TEM - Setup 2

TEM - Setup 3

TEM - Setup 4

TEM - Setup 5

TEM - Setup 6

Figure 76. Main cabin to main cabin TEM antenna data insertion 

loss data at each of the six positions and one repeat position.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Main Cabin 

TEM - Setup 1 (door open)

TEM - Setup 2

TEM - System NOISE (acu on)

TEM - System NOISE (acu off)

Figure 77. Main cabin to main cabin TEM antenna data for the 

maximum insertion loss, the minimum insertion loss and two 

noise measurements.
65 

blue, solid trace) plotted against the theoretical cumulative distribution function. This plot shows 

that the data does not tightly follow the theoretical cumulative distribution function. This does 

not typically seem to be the case for the individual positions. 

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 - 100 

MHz

Group 2 - 500 

MHz

Group 3 - 1 

GHz

Group 4 - 1.5 

GHz

Group 5 - 2 

GHz

Group 6 - 2.5 

GHz

Figure 78. Whisker-box plots for all main cabin to main cabin insertion loss measurements of 

the TEM horn antennas at several frequencies. 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

50

100

150

200

250

Number of Bins

TEM

Main Cabin to Main Cabin

(all setups)

Figure 79. Chi-squared probability density function for all 

measurements in the main cabin to main cabin insertion loss 

measurements.
66 

6.4.1.1 Individual TEM horn antenna measurement positions 

In this section each measurement position is individually analyzed. Figures 81 to 92 show a 

photograph of the measurement positions, a time-domain plot and a schematic of the inside of 

the737-200 that indicates where the antennas were placed. 

-90 -80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Main Cabin

(all setups)

Figure 80. Chi-squared cumulative density function for all 

measurements in the main cabin to main cabin insertion loss 

measurements.
67 

Figure 81 shows the placement for the transmitting and receiving TEM horn antennas in the 

main cabin for setup 1 and measurements 1 and 2. The horizontally polarized 1.2 m TEM horn 

antenna was located in the rear of the aircraft on a piece of closed-cell foam and pointed toward 

the back of the aircraft. The vertically polarized 36 cm antenna was located in the first-class 

section of the aircraft and pointed toward the front of the aircraft. The antennas were not 

boresighted and therefore no direct components exist in this measurement, as shown in the timedomain graph of Figure 82. Two measurements were taken, one with the main cabin passenger 

door open and one with it closed. The graph in Figure 82 shows only minor differences exist 

between having the door open or closed. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 1

TEM - Setup 1 

 (FD door open)

Figure 82. Main cabin to main cabin TEM horn 

antenna setup 1, time-domain response.

Figure 81. Main cabin to main cabin TEM horn antenna setup 1.
68 

Figure 83 shows the placement of the transmitting and receiving TEM horn antennas in the main 

cabin for setup 2, measurements 1 and 2. The vertically polarized 1.2 m TEM horn antenna was 

located in the rear of the aircraft on a piece of closed-cell foam centered over the aisle. The 

vertically polarized 36 cm antenna was located in the first-class section of the aircraft toward the 

front and was also placed on a piece of closed-cell foam centered over the aisle. The antennas 

were intentionally boresighted in this setup to help us understand how the direct component can 

influence the statistics. A time-domain graph of this measurement is shown in Figure 84. The 

time domain is used to help us understand relationship between the direct component and 

reverberant fields. Figure 84 shows the waveform including the direct component (black trace), 

and another waveform with the direct component gated out (red trace). 

Figure 84. Main cabin to main cabin TEM horn 

antenna setup 2,time-domain response.

Figure 83. Main cabin to main cabin TEM horn 

antenna setup.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 2

TEM - Setup 2 - 

 No Direct Component

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 2

TEM - Setup 2 - 

 No Direct Component
69 

Figure 85 shows the placement of the transmitting and receiving TEM horn antennas in the main 

cabin for setup 3, measurements 1 and 2. The vertically polarized 1.2 m TEM horn antenna was 

left in the same location as for setup 2, which was on a piece of closed-cell foam centered over 

the aisle at the rear of the aircraft. The 36 cm TEM horn antenna was located in an overhead 

compartment in the first-class section of the aircraft and pointed toward the front of the aircraft. 

The overhead compartment door was open. The time-domain waveform is shown in Figure 86. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 3

Figure 86. Main cabin to main cabin TEM horn 

antenna setup 3, time-domain response.

Figure 85. Main cabin to main cabin TEM horn antenna setup 3.
70 

Figure 87 shows the placement of the transmitting and receiving DRG horn antennas in the main 

cabin for setup 4. The 1.2 m TEM horn antenna was located in the rear of the aircraft on a piece 

of closed-cell foam facing the passenger windows toward the front of the aircraft. The 36 cm 

antenna was located in an overhead compartment in the first-class section of the aircraft and 

pointed toward the front of the aircraft, as in setup 3. The compartment was partially closed. 

The time-domain waveform is shown in Figure 88. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 4

Figure 88. Main cabin to main cabin TEM horn 

antenna setup 4, time-domain response.

Figure 87. Main cabin to main cabin TEM horn antenna setup 4.
71 

Figure 89 shows the placement of the transmitting and receiving TEM horn antennas in the main 

cabin for setup 5. The 1.2 m TEM horn antenna was on a piece of closed-cell foam the rear of 

the aircraft in the same configuration as for Setup 4. The vertically polarized 36 cm TEM horn 

antenna was located on the floor the first-class section of the aircraft and pointed toward the side 

of the aircraft. The time-domain waveform is shown in Figure 90. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 5

Figure 90. Main cabin to main cabin TEM horn 

antenna setup 5, time-domain response.

Figure 89. Main cabin to main cabin TEM horn antenna setup 5.
72 

Figure 91 shows the placement of the transmitting and receiving TEM horn antennas in the main 

cabin for setup 6, measurements 1 and 2. Both antennas were placed on the floor of the main 

cabin. The horizontally polarized 1.2 m TEM horn antenna was located in the rear of the aircraft 

and pointed toward the front of the aircraft along the aisle. The vertically polarized 36 cm TEM 

horn antenna was located on the floor just behind the first-class section of the aircraft and 

pointed toward the rear of the aircraft. The time-domain waveform is shown in Figure 92. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Main Cabin

TEM - Setup 6

Figure 92 Main cabin to main cabin TEM horn 

antenna setup 6, time-domain response.

Figure 91. Main cabin to main cabin TEM horn antenna setup 6.
73 

Figure 93 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 1 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 2 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2

statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup from 

Figure 94 to Figure 97. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 1

- door

open

Setup 1

- meas 1

Setup 2

- meas 2

Setup 2

- meas 1

Setup 3

- meas 2

Setup 3

- meas 1 Setup 4 Setup 5

Setup 6

- meas 2

Setup 6

- meas 1

Figure 93. Whisker-box plots for the TEM horn antennas for main cabin to main cabin insertion loss.
74 

Setup 

1 door 

open

Setup1 

door 

closed

Setup 

2 meas

1

Setup 

2 meas

2

Setup 

3 meas

1

Setup 

3 meas

2

Setup 

4

Setup 

5

Setup 

6 meas

1

Setup 

6 meas

2

Mean 

(dB) −63.99 −63.08 −44.98 −45.62 −53.09 −50.75 −57.75 −57.15 −51.08 −53.24

Median 

(dB) −63.11 −61.79 −45.12 −45.19 −51.43 −50.10 -57.09 −56.40 −50.51 −52.07

Standard 

Deviation 

(dB)

5.28 5.98 4.64 5.60 5.58 4.65 4.53 5.04 5.15 6.08

Minimum 

(dB) −85.79 −85.47 −64.56 −73.12 −78.71 −64.27 −70.59 −82.58 −78.92 −78.78

Maximum 

(dB) −54.35 −54.47 −37.31 −37.69 −44.19 −43.88 −48.90 −48.47 −41.73 −42.07

Setup 

1 door 

open

Setup1 

door 

closed

Setup 

2 meas

1

Setup 

2 meas

2

Setup 

3 meas

1

Setup 

3 meas

2

Setup 

4

Setup 

5

Setup 

6 meas

1

Setup 

6 meas

2

Mean 

(dB) −63.99 −63.08 −44.98 −45.62 −53.09 −50.75 −57.75 −57.15 −51.08 −53.24

Median 

(dB) −63.11 −61.79 −45.12 −45.19 −51.43 −50.10 -57.09 −56.40 −50.51 −52.07

Standard 

Deviation 

(dB)

5.28 5.98 4.64 5.60 5.58 4.65 4.53 5.04 5.15 6.08

Minimum 

(dB) −85.79 −85.47 −64.56 −73.12 −78.71 −64.27 −70.59 −82.58 −78.92 −78.78

Maximum 

(dB) −54.35 −54.47 −37.31 −37.69 −44.19 −43.88 −48.90 −48.47 −41.73 −42.07

Table 1. TEM horn internal cabin statistics for measurements from the main cabin to the main cabin. The 

sample size was 321 points which were in a 200 MHz bandwidth around a center frequency of 1 GHz.

Table 2. TEM horn antenna internal cabin 2-distribution statistics for measurements from the main cabin to the main cabin.

Setup 1 

door 

open

Setup1 

door 

closed

Setup 2 

meas 1

Setup 2 

meas 2

Setup 3 

meas 1

Setup 3 

meas 2 Setup 4 Setup 5 Setup 6 

meas 1

Setup 6 

meas 2

Whisker-Box 

Plot Mean (dB) −63.99 −63.08 −44.92 −45.62 −53.09 − 50.75 −57.75 −57.15 −51.08 −53.24

Χ2 Mean (dB) −62.00 −61.00 −35.00 −34.00 −50.00 −47.00 −56.00 −62.00 −63.00 −59.00

 (dB) −1.00 −2.00 −10.00 −11.00 −3.00 −3.00 −2.00 +5.00 +13.00 +6.00

Setup 1 

door 

open

Setup1 

door 

closed

Setup 2 

meas 1

Setup 2 

meas 2

Setup 3 

meas 1

Setup 3 

meas 2 Setup 4 Setup 5 Setup 6 

meas 1

Setup 6 

meas 2

Whisker-Box 

Plot Mean (dB) −63.99 −63.08 −44.92 −45.62 −53.09 − 50.75 −57.75 −57.15 −51.08 −53.24

Χ2 Mean (dB) −62.00 −61.00 −35.00 −34.00 −50.00 −47.00 −56.00 −62.00 −63.00 −59.00

 (dB) −1.00 −2.00 −10.00 −11.00 −3.00 −3.00 −2.00 +5.00 +13.00 +6.00
75 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 1 (door closed)

-100 -90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 1 (door closed)

Figure 94. Chi-squared plots for TEM horn antenna, setup 1, measurement 1 (door open and closed),and setup 2, measurement 1, for the main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 1 (door open)

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 1 (door open)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

80604020

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 2

-60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 2
76 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

604020

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 2 - m2

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 2 - m2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 3

-90 -80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 3

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 2 - no direct component

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 2 - no direct component

Figure 95. Chi-squared plots for TEM horn antenna, setup 2, measurement 2, setup 2, no direct component, and setup 3, measurement 1 for the main cabin to main cabin insertion loss.
77 

Figure 96. Chi-squared plots for TEM horn antenna, setup 3, measurement 2, setup 4, and setup 5, for the main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 3 - m2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 4

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 5

-100 -90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 5

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 4

-70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 3 - m2
78 

Figure 97. Statistical analysis for TEM horn antenna, setup 6-measurement 1, and setup 6, measurement 2, for 

main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 6

-100 -90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 6

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Main Cabin

Setup 6 - m2

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Main Cabin

Setup 6 - m2
79 

6.4.1.3 Combined DRG horn antenna positions 

Six positions were measured, with one repeat measurement for two of the positions. The 

antennas were not moved for the reposition, the data were just retaken. Figure 98 shows results 

for all measurements in the main cabin for the TEM horn antenna showing a maximum insertion 

loss of around −30 dB and a minimum insertion loss of around −65 dB. Figure 99 show results 

for the measurement of maximum cabin insertion loss, the minimum insertion loss, and two 

system noise floors. One noise-floor measurement was taken with the DRG antennas positioned 

in setup 1, and the other noise-floor measurement was taken with the antennas positioned in 

setup 4. 

For the DRG horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz, 

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in 

Figure 97. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a 

total of 2247 points will be in the statistical bandwidth. The results from the 900 MHz set and 

the 1000 MHz for the DRG horn antenna sets may not be completely statistically independent 

but it was important to stay away from the band edges of the measurement; and it was also 

important to include enough information for reliable processing. Figure 100 shows the median 

insertion loss across the frequency bandwidth range from about −40 dB to −50 dB. The 

maximum insertion loss for these frequencies is approximately −21 dB in a 200 MHz bandwidth 

around a center frequency of 1500 MHz; and the minimum insertion loss is −100 dB in a 

200 MHz bandwidth around a center frequency of 1000 MHz. 

The χ

2

 pdf for all TEM horn antenna measurements is shown in Figure 101, and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 102. The histogram in Figure 101 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −38 dB. Figure 102 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 
80 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

DRG - Setup 7 (meas 1)

DRG - Setup 7 (meas 2)

DRG - Setup 8

DRG - Setup 9

DRG - Setup 10

DRG - Setup 11

DRG - Setup 12

Figure 98. Main cabin to main cabin DRG antenna insertion loss 

data at each of the six positions and one repeat position.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Main Cabin 

DRG - Setup 7 (meas 1)

DRG - Setup 8

DRG - Setup 10 NOISE

DRG - Setup 10 NOISE (meas 4)

Figure 99. Main cabin to main cabin DRG antenna data for the 

maximum insertion loss, the minimum insertion loss, and two 

noise measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Main Cabin 

DRG - Setup 7 (meas 1)

DRG - Setup 8

DRG - Setup 10 NOISE

DRG - Setup 10 NOISE (meas 4)

Figure 99. Main cabin to main cabin DRG antenna data for the 

maximum insertion loss, the minimum insertion loss, and two 

noise measurements.
81 

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

900 MHz

Group 2 - 1

GHz

Group 3 -

1.5 GHz

Group 4 - 2

GHz

Group 5 -

2.5 GHz

Figure 100. Whisker-box plots for all main cabin to main cabin insertion 

loss measurements of the DRG horn antennas at several frequencies.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

50

100

150

200

250

Number of Bins

DRG

Main Cabin to Main Cabin

(all setups)

Figure 101. Chi-squared probability density function for all 

setups in the main cabin to main cabin insertion loss 

measurements.
82 

6.4.1.4 Individual DRG horn antenna positions 

A photograph for each DRG antenna to DRG antenna measurement position, its associated timedomain waveform, and a schematic showing the antenna positions inside the aircraft is shown 

from Figure 103 to Figure 114. The time-domain waveforms provide information for any direct 

antenna coupling components that may exist and the reverberant decay characteristics of the 

cavity-to-cavity interaction. 

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Main Cabin

(all setups)

Figure 102. Chi-squared cumulative density function for all 

setups in the main cabin to main cabin insertion loss 

measurements.
83 

Figure 103 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 7, measurements 1 and 2. Measurement 2 is a repeat measurement; the 

antennas were not moved. Unfortunately, this is the only photograph we have and it is out of 

focus. One antenna was vertically polarized and located in the rear of the aircraft on a piece of 

closed-cell foam centered over the aisle. The other antenna was located in the first-class section 

of the aircraft toward the front and was also placed on a piece of closed-cell foam centered over 

the aisle in the vertical polarization. The antennas were intentionally boresighted in this setup to 

help us understand how the direct component can influence the statistics. Figure 104 is a timedomain graph showing a measurement with the direct antenna coupling component (black trace) 

and without the direct antenna coupling component with only the reverberant fields (red trace). 

Figure 103. Main cabin to main cabin DRG horn antenna setup 7.

Figure 104. Main cabin to main cabin DRG horn antenna 

setup 7, time-domain response.

0 40 80 120 160 200

Time (ns)

-0.005

-0.004

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.005

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 7

DRG - Setup 7 - 

 No direct component
84 

Figure 105 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 8. One antenna was horizontally polarized and located in the rear of the 

aircraft on a piece of closed-cell foam pointing toward the back of the aircraft. The other, 

vertically polarized antenna was located in the first-class section of the aircraft and pointed 

toward the front of the aircraft. The antennas were not boresighted, and therefore no direct 

components exist in this measurement, as shown in the time-domain graph of Figure 106. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 8

Figure 106. Main cabin to main cabin DRG horn 

antenna setup 8, time-domain response.

Figure 105. Main cabin to main cabin DRG horn antenna setup 8.
85 

Figure 107 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 9. One vertically polarized antenna was located in the rear of the aircraft on 

a piece of closed-cell foam centered over the aisle in the same position as in setup 7. The other 

antenna was located in an overhead compartment in the first-class section of the aircraft and 

pointed toward the front of the aircraft. The compartment was left open. The time-domain graph 

is shown in Figure 108. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 9

Figure 108. Main cabin to main cabin DRG horn 

Figure107. Main cabin to main cabin DRG horn antenna setup. 9
86 

Figure 109 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 10, measurements 1 and 2. One vertically polarized antenna was located in 

the rear of the aircraft on a piece of closed-cell foam centered over the aisle, as in setup 9. The 

other antenna was located in an overhead compartment in the first-class section of the aircraft 

and pointed toward the front of the aircraft, but the overhead compartment door was then closed. 

The time-domain graph is shown in Figure 110. By comparing Figure 108 and Figure 110 we 

can see there is little difference in amplitude between closing the overhead compartment and 

leaving it open. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 10

Figure 110. Main cabin to main cabin DRG horn 

antenna setup 10, time-domain response.

Figure 109. Main cabin to main cabin DRG horn antenna setup 10.
87 

Figure 111 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 11. One vertically polarized antenna was located in the rear of the aircraft 

on a piece of closed-cell foam pointing toward the center and outside of the aircraft. The other 

vertically polarized antenna was located on the floor the first-class section of the aircraft and 

pointed toward the outside of the aircraft. The time-domain graph is shown in Figure 112. 

Figure 112. Main cabin to main cabin DRG horn 

antenna setup 11, time-domain response.

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 11

Figure 111. Main cabin to main cabin DRG horn antenna setup 11.
88 

Figure 113 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 12. Both antennas were placed on the floor of the main cabin. One 

horizontally polarized antenna was located in the rear of the aircraft and pointed toward the front 

of the aircraft along the aisle. The other vertically polarized antenna was located on the floor just 

behind the first class section of the aircraft and pointed toward the rear of the aircraft. The 

antennas were not boresighted, and therefore no direct components exist in this measurement as 

shown in the time-domain graph of Figure 114. 

0 100 200 300

Time (ns)

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

Normalized Signal Amplitude

Main Cabin to

Main Cabin

DRG - Setup 12

Figure 114. Main cabin to main cabin DRG horn 

antenna setup 12, time-domain response.

Figure 113. Main cabin to main cabin DRG 

horn antenna setup 12.
89 

A statistical analysis is presented in the next few graphs. A whisker-box plot is shown for each 

DRG horn antenna in Figure 115, and Table 3 shows the mean value, the median value, the 

standard deviation, the maximum value, and the minimum value. The statistics for each setup 

were taken over a 200 MHz bandwidth (equivalent to 321 data points) centered around a 

frequency of 1000 MHz. The chi-squared χ

2

 pdf and the χ

2

 cdf statistical descriptions are shown 

in Figures 116 to Figure 117, and Table 4 compares the mean of general statistical analysis, the 

mean from the analysis of the χ

2 distribution, and the difference between these two means. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 7 -

Meas 1

Setup 7 -

Meas 2 Setup 8 Setup 9

Setup 10 

- Meas 1

Setup 10

- Meas 2 Setup 11 Setup 12

Figure 115. Whisker-box plots for the DRG horn antennas for setups 7 to 10. These 

data are from measurements of main cabin to main cabin insertion loss.

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 7 -

Meas 1

Setup 7 -

Meas 2 Setup 8 Setup 9

Setup 10 

- Meas 1

Setup 10

- Meas 2 Setup 11 Setup 12

Figure 115. Whisker-box plots for the DRG horn antennas for setups 7 to 10. These 

data are from measurements of main cabin to main cabin insertion loss.
90 

Setup 7 

meas 1

Setup7 

meas 2

Setup 7 

no 

direct

Setup 8 Setup 9 Setup 

10

Setup 

10 redo

Setup 

11

Setup 

12

Mean 

(dB) -37.85 -36.40 -42.44 -56.92 -46.98 -46.25 -44.46 -47.41 -41.10

Median 

(dB) -36.69 -35.12 -40.71 -56.47 -45.89 -44.76 -43.76 -46.72 -39.90

Standard 

Deviation 

(dB)

6.25 6.19 5.07 5.19 5.63 5.42 5.03 5.50 5.73

Minimum 

(dB) -57.95 -61.68 -66.28 -100.92 -68.21 -70.77 -66.72 -76.71 -62.97

Maximum 

(dB) -29.15 -27.83 -36.44 -48.30 -38.34 -36.37 -35.71 -38.49 -31.16

Setup 7 

meas 1

Setup7 

meas 2

Setup 7 

no 

direct

Setup 8 Setup 9 Setup 

10

Setup 

10 redo

Setup 

11

Setup 

12

Mean 

(dB) -37.85 -36.40 -42.44 -56.92 -46.98 -46.25 -44.46 -47.41 -41.10

Median 

(dB) -36.69 -35.12 -40.71 -56.47 -45.89 -44.76 -43.76 -46.72 -39.90

Standard 

Deviation 

(dB)

6.25 6.19 5.07 5.19 5.63 5.42 5.03 5.50 5.73

Minimum 

(dB) -57.95 -61.68 -66.28 -100.92 -68.21 -70.77 -66.72 -76.71 -62.97

Maximum 

(dB) -29.15 -27.83 -36.44 -48.30 -38.34 -36.37 -35.71 -38.49 -31.16

Table 3. DRG horn internal cabin statistics for measurements from the main cabin to the main cabin. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 7 

meas 1

Setup7 

meas 2

Setup 7 no 

direct Setup 8 Setup 9 Setup 10 Setup 10 redo Setup 11 Setup 12

Whisker-Box 

Plot Mean (dB) −37.85 −36.40 − 42.44 −56.92 − 46.98 − 46.25 − 44.46 − 47.41 − 41.10

Χ2 Mean (dB) −35.00 −31.00 −41.00 −57.00 − 44.00 − 43.00 − 43.00 − 44.00 − 33.00

 (dB) − 3.00 − 4.00 − 1.00 > +1.00 − 3.00 − 2.00 − 1.50 − 3.00 − 7.00

Setup 7 

meas 1

Setup7 

meas 2

Setup 7 no 

direct Setup 8 Setup 9 Setup 10 Setup 10 redo Setup 11 Setup 12

Whisker-Box 

Plot Mean (dB) −37.85 −36.40 − 42.44 −56.92 − 46.98 − 46.25 − 44.46 − 47.41 − 41.10

Χ2 Mean (dB) −35.00 −31.00 −41.00 −57.00 − 44.00 − 43.00 − 43.00 − 44.00 − 33.00

 (dB) − 3.00 − 4.00 − 1.00 > +1.00 − 3.00 − 2.00 − 1.50 − 3.00 − 7.00

Table 4. DRG horn antenna internal cabin Χ2-distribution statistics for measurements from the main cabin to the main cabin. 
91 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 7_m1

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 7_m1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 7_m2

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 7_m2

Figure 116. Chi-squared plots for DRG horn antenna, setup 7, measurement 1, measurement 2, and statistics with no direct component for the main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 7 - no direct component

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 7 - no direct component
92 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 8

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 8

Figure 117. Statistical analysis for DRG horn antenna, setups 8, 9, and 10 (measurement 1) for the main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 9

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 9

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 10

-70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 10
93 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 10 - repeat

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 10-redo

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 11

-70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

Main Cabin to Main Cabin

Setup 11

-70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 12

-60 -40 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

Main Cabin to Main Cabin

Setup 12

Figure 118. Statistical analysis for DRG horn antenna, setups 10 (measurement 2), 11, and 12 for the main cabin to main cabin insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 10 - repeat

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Main Cabin

Setup 10-redo

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 11

-70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

Main Cabin to Main Cabin

Setup 11

-70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 12

-60 -40 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

Main Cabin to Main Cabin

Setup 12

Figure 118. Statistical analysis for DRG horn antenna, setups 10 (measurement 2), 11, and 12 for the main cabin to main cabin insertion loss.
94 

6.4.2 Main Cabin to Flight Deck 

The DRG and TEM horn antennas were measured at various positions between the main cabin 

and flight deck. In general, for each compartment-to-compartment measurement, we tried to 

position them in approximately the same position for each of these runs. 

6.4.2.1 Combined DRG horn antenna positions 

Four positions were measured for the DRG antenna type with a repeat measurement with the 

flight deck to main cabin door closed for positions 1 and 3. Figure 119 shows all measurement 

results for the DRG horn antenna showing a maximum insertion loss of around −50 dB and 

minimum insertion loss of around −65 dB. Figure 120 shows the results for the measurement 

having maximum cabin insertion loss, minimum insertion loss, and two system noise floor 

measurements. There were no noise-floor measurements taken with the DRG horn antennas; the 

TEM horn antenna data were used for the noise floor. The noise-floor measurement shown by 

the gold trace was the system noise floor taken by putting a 50 ohm load on the receiving side of 

the system. The purple trace is the ambient noise floor taken by putting the 50 ohm load on the 

transmitting side and looking for the ambient that enters the receiving antenna. Both were 

averaged over a 200 MHz bandwidth. 

Whisker-box plots are shown in Figure 121 for the following center frequencies, (1) 100 MHz, 

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these 

plots are from a 200 MHz bandwidth around each center frequency. These plots show that the 

median insertion loss for these frequencies has values from about −50 dB to −60 dB. The 

maximum insertion loss for these frequencies is approximately −44 dB in a 200 MHz bandwidth 

around a center frequency of 1500 MHz, and the minimum insertion loss is −100 dB dB in a 

200 MHz bandwidth around a center frequency of 100 MHz. 
95 

The χ

2

 pdf for all DRG horn antenna measurements is shown in Figure 122, and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 123. The histogram in Figure 122 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −53 dB. Figure 123 is the data (dark-blue, solid trace) plotted 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

DRG - Setup 1

DRG - Setup 1 (FD door closed)

DRG - Setup 2

DRG - Setup 3

DRG - Setup 3 (FD door closed)

DRG - Setup 4

Figure 119. Main cabin to flight deck DRG antenna insertion loss

data at each of the four positions, and two repeat measurements 

with the flight deck door closed.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

DRG - Setup 1

DRG - Setup 1 (FD door closed)

DRG - Setup 2

DRG - Setup 3

DRG - Setup 3 (FD door closed)

DRG - Setup 4

Figure 119. Main cabin to flight deck DRG antenna insertion loss

data at each of the four positions, and two repeat measurements 

with the flight deck door closed.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

DRG - Setup 3

DRG - Setup 2

TEM - System NOISE

TEM - Ambient NOISE

Figure 120. Main cabin to flight deck DRG horn antenna data for 

the maximum and minimum insertion loss, and two TEM horn 

antenna noise measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

DRG - Setup 3

DRG - Setup 2

TEM - System NOISE

TEM - Ambient NOISE

Figure 120. Main cabin to flight deck DRG horn antenna data for 

the maximum and minimum insertion loss, and two TEM horn 

antenna noise measurements.
96 

against the theoretical cumulative distribution function. This plot shows that the data do not 

tightly follow the theoretical cumulative distribution function. This does not typically seem to be 

the case for the individual positions. 

Figure 121. Whisker-box plots of all main cabin to flight deck insertion-loss 

measurements for the DRG horn antennas at several frequencies. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Group 1 -

900 MHz

Group 2 - 1 

GHz

Group 3 - 1.5 

GHz

Group 4 - 2 

GHz

Group 5 - 2.5 

GHz

Figure 121. Whisker-box plots of all main cabin to flight deck insertion-loss 

measurements for the DRG horn antennas at several frequencies. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Group 1 -

900 MHz

Group 2 - 1 

GHz

Group 3 - 1.5 

GHz

Group 4 - 2 

GHz

Group 5 - 2.5 

GHz

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

200

Number of Bins

DRG

Main Cabin to Flight Deck

(all setups)

Figure 122. Chi-squared probability density function for all setups in the 

main cabin to flight deck insertion-loss measurements.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

200

Number of Bins

DRG

Main Cabin to Flight Deck

(all setups)

Figure 122. Chi-squared probability density function for all setups in the 

main cabin to flight deck insertion-loss measurements.
97 

6.4.2.2 Individual DRG horn antenna measurement positions 

In this section each measurement position from the main cabin to the flight deck is individually 

analyzed. Figures 124 to 131 show photographs of the locations of the antennas in the flight 

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that 

indicates where the antennas were placed. 

Figure 123. Chi-squared cumulative density function for all setups in the 

main cabin to flight deck insertion loss measurements.

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Flight Deck

(all setups)
98 

Figure 124 shows the placement for the transmitting and receiving DRG horn antennas in the 

main cabin for setup 1, measurements 1 and 2. The flight deck door was open for measurement 1 

and closed for measurement 2. One horizontally polarized antenna was located in the rear of the 

aircraft on the floor of the main passenger cabin. The other antenna was located in the pilot’s 

seat in the flight deck of the aircraft and pointed toward the ceiling. The graph in Figure 125 

shows there is a slight difference between having the door open or closed, noticeable at the 

beginning of the waveform; however, the decay of the fields seem to be the same.

Figure 124. Main cabin to flight deck DRG horn antenna setup.

0 100 200 300

Time (ns)

-0.0005

-0.0004

-0.0003

-0.0002

-0.0001

0

0.0001

0.0002

0.0003

0.0004

0.0005

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 1

DRG - Setup 1 

 (FD door closed)

Figure 125. Main cabin to flight deck DRG horn 

antenna setup 1, time-domain response.

Figure 124. Main cabin to flight deck DRG horn antenna setup.

0 100 200 300

Time (ns)

-0.0005

-0.0004

-0.0003

-0.0002

-0.0001

0

0.0001

0.0002

0.0003

0.0004

0.0005

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 1

DRG - Setup 1 

 (FD door closed)

Figure 125. Main cabin to flight deck DRG horn 

antenna setup 1, time-domain response.

0 100 200 300

Time (ns)

-0.0005

-0.0004

-0.0003

-0.0002

-0.0001

0

0.0001

0.0002

0.0003

0.0004

0.0005

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 1

DRG - Setup 1 

 (FD door closed)

Figure 125. Main cabin to flight deck DRG horn 

antenna setup 1, time-domain response.
99 

Figure 126 shows the placements of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 2, measurements 1 and 2. One horizontally polarized antenna was located 

in the rear of the aircraft on the floor of the main passenger cabin. The other horizontally 

polarized antenna was located in the co-pilot’s seat in the flight deck of the aircraft and pointed 

toward the left side. A time-domain graph of this measurement is shown in Figure 127. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 2

Figure 127. Main cabin to flight deck DRG horn 

antenna setup 2, time-domain response.

Figure 126. Main cabin to flight deck DRG horn antenna setup 2.
100 

Figure 128 shows the placement of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 3, measurements 1 and 2. For this position we also took one measurement 

with the flight deck door open and one with the flight deck door closed. One vertically polarized 

antenna was located in the first class section over a seat. The other horizontally polarized 

antenna was located in the co-pilot’s seat in the flight deck of the aircraft and pointed toward the 

left side. The time-domain waveform is shown in Figure 129. The time-domain graphs show 

only slight differences between the two measurements. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 3

DRG - Setup 3

 (FD door closed)

Figure 129. Main cabin to flight deck DRG 

horn antenna setup 3, time-domain response.

Figure 128. Main cabin to flight deck DRG horn antenna setup 3.
101 

Figure 130 shows the placements of the transmitting and receiving DRG horn antennas in the 

main cabin for setup 4. One vertically polarized antenna was located in the first class section 

over a seat. The other horizontally polarized antenna was located on the floor by the co-pilot’s 

seat and pointed toward the front of the aircraft. The compartment was partially closed. The 

time-domain waveform is shown in Figure 131. 

Figure 130. Main cabin to flight deck DRG horn antenna setup 4.

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

DRG - Setup 4

Figure 131. Main cabin to flight deck DRG horn 

antenna setup 4, time-domain response.
102 

Figure 132 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 5 summarizes the statistics of each setup for the whisker-box plots, including the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 6 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ2

statistic. The difference between the 

two means is also displayed. Finally, the χ2

 pdf and the χ2 cdf are plotted for each setup in 

Figure 133 and Figure 134. 

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Setup 1-

door open

Setup 1-

door closed Setup 2

Setup 3-

door closed

Setup 3-

door open Setup 4

Figure 132. Whisker-box plots for the DRG horn antennas for main cabin to flight deck insertion loss.
103 

Setup 1 

door open

Setup1 

door closed

Setup 2 

meas 1

Setup 3 

door open

Setup 3 

door closed Setup 4

Mean (dB) −58.37 −59.78 −63.98 −54.08 −53.07 −55.21

Median 

(dB) −57.11 −59.02 −62.06 −52.87 −51.89 −53.95

Standard 

Deviation 

(dB)

5.28 4.88 6.25 6.70 6.08 6.35

Minimum 

(dB) −81.94 −85.55 −82.42 −77.53 −74.91 −77.17

Maximum 

(dB) −50.31 −49.82 −54.90 −44.03 −43.64 −44.83

Setup 1 

door open

Setup1 

door closed

Setup 2 

meas 1

Setup 3 

door open

Setup 3 

door closed Setup 4

Mean (dB) −58.37 −59.78 −63.98 −54.08 −53.07 −55.21

Median 

(dB) −57.11 −59.02 −62.06 −52.87 −51.89 −53.95

Standard 

Deviation 

(dB)

5.28 4.88 6.25 6.70 6.08 6.35

Minimum 

(dB) −81.94 −85.55 −82.42 −77.53 −74.91 −77.17

Maximum 

(dB) −50.31 −49.82 −54.90 −44.03 −43.64 −44.83

Table 5. DRG horn internal cabin statistics for measurements from the main cabin to the flight deck. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Table 6. DRG horn antenna internal cabin Χ2 - distribution statistics for measurements from the main 

cabin to the flight deck. 

Setup 1 

door open

Setup1 

door closed

Setup 2 

meas 1

Setup 3 

door open

Setup 3 

door closed Setup 4

WhiskerBox Plot 

Mean (dB)

−58.37 −59.78 −63.98 −54.08 −53.07 −55.21

Χ2 Mean 

(dB) −57.00 −55.00 −58.00 −54.00 −52.00 −52.00

 (dB) −1.00 −5.00 − 6.00 < −1.00 − 1.00 − 3.00

Setup 1 

door open

Setup1 

door closed

Setup 2 

meas 1

Setup 3 

door open

Setup 3 

door closed Setup 4

WhiskerBox Plot 

Mean (dB)

−58.37 −59.78 −63.98 −54.08 −53.07 −55.21

Χ2 Mean 

(dB) −57.00 −55.00 −58.00 −54.00 −52.00 −52.00

 (dB) −1.00 −5.00 − 6.00 < −1.00 − 1.00 − 3.00
104 

Figure 133. Chi-squared plots for TEM horn antenna, setup 1, flight deck door open and closed, and setup 2, for the main cabin to flight deck insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Flight Deck

Setup 1 

(flight deck door open)

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 1

(flight deck door open)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Flight Deck

Setup 1 

 (flight deck door closed)

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 1

(flight deck door closed)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Flight Deck

Setup 2

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 2
105 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Flight Deck

Setup 3

(flight deck door open)

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 3

(flight deck door open)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Flight Deck

Setup 3

(flight deck door closed)

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 3

flight deck door closed

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Main Cabin

Setup 4

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Flight Deck

Setup 4

Figure 134. Chi-squared plots for TEM horn antenna, setup 3, flight deck door open and closed, and setup 4, for the main cabin to flight deck insertion loss.
106 

6.4.2.3 Combined TEM horn antenna positions 

Six positions were measured for the TEM horn antenna type, with a repeat measurement for 

position 8. The antennas were not moved for the reposition, the data were just retaken. Figure 

135 shows results for all measurement results in the main cabin for the TEM horn antenna 

showing a maximum insertion loss of around −50 dB and a minimum insertion loss of around 

−75 dB. Figure 136 show results for the maximum cabin insertion loss measurement, the 

minimum insertion loss measurement, and two system noise floors. 

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz, 

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in 

Figure 97. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a 

total of 2247 points will be in the statistical bandwidth. The results from the 900 MHz set and 

the 1000 MHz for the TEM horn antenna sets may not be completely statistically independent, 

but it was important to stay away from the band edges of the measurement, and it was also 

important to include enough information for reliable processing. Figure 137 shows the median 

insertion loss across the frequency bandwidth range from about −65 dB to −90 dB. The 

maximum insertion loss for these frequencies is approximately −50 dB in a 200 MHz bandwidth 

around a center frequency of 1500 MHz, and the minimum insertion loss is −140 dB in a 

200 MHz bandwidth around a center frequency of 1000 MHz. 

The χ

2

 pdf for all TEM horn antenna measurements is shown in Figure 138, and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 139. The histogram in Figure 138 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −62 dB. Figure 139 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 
107 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

TEM - Setup 5

TEM - Setup 6

TEM - Setup 7

TEM - Setup 8 (meas 1)

TEM - Setup 8 (meas 2)

TEM - Setup 9

TEM - Setup 10

Figure 135. Main cabin to flight deck TEM antenna insertion loss 

data at each of the six positions and one repeat measurement at 

position 8.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

TEM - Setup 5

TEM - Setup 6

TEM - Setup 7

TEM - Setup 8 (meas 1)

TEM - Setup 8 (meas 2)

TEM - Setup 9

TEM - Setup 10

Figure 135. Main cabin to flight deck TEM antenna insertion loss 

data at each of the six positions and one repeat measurement at 

position 8.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

TEM - Setup 5

TEM - Setup 9

TEM - System NOISE

TEM - Ambient NOISE

Figure 136. Main cabin to flight deck TEM horn antenna data for 

the maximum insertion loss, the minimum insertion loss, and two 

noise measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Flight Deck 

TEM - Setup 5

TEM - Setup 9

TEM - System NOISE

TEM - Ambient NOISE

Figure 136. Main cabin to flight deck TEM horn antenna data for 

the maximum insertion loss, the minimum insertion loss, and two 

noise measurements.
108 

-160.00

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

100 MHz

Group 2 -

500 MHz

Group 3 - 1

GHz

Group 4 -

1.5 GHz

Group 5 - 2

GHz

Group 6 -

2.5 GHz

Figure 137. Whisker-box plots for all main cabin to flight deck insertion loss measurements 

of the TEM horn antennas at several frequencies. 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

200

Number of Bins

TEM

Main Cabin to Flight Deck

(all setups)

Figure 138. Chi-squared probability density function for all 

setups in the main cabin to flight deck insertion loss 

measurements.
109 

6.4.2.4 Individual TEM horn antenna positions 

Figures 140 to Figure 149 include a photograph for each TEM antenna measurement location 

from the main cabin to the flight deck, its associated time-domain waveform, and a schematic 

showing the antenna positions inside the aircraft. 

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Flight Deck

(all setups)

Figure 139. Chi-squared cumulative density function for all 

setups in the main cabin to flight deck insertion loss 

measurements.
110 

Figure 140 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 5. The 

vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft across the 

center aisle. The horizontally polarized 36 cm TEM horn antenna was located on the floor by the 

co-pilot’s seat and pointed toward the front of the aircraft. Figure 141 is a time-domain graph 

showing a measurement with the direct antenna coupling component (black trace) and without 

the direct antenna coupling component with only the reverberant fields (red trace). 

Figure 140. Main cabin to flight deck TEM horn antenna setup 5.

Figure 141. Main cabin to flight deck TEM horn 

antenna setup 5, time-domain response.

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

TEM - Setup 5
111 

Figure 142 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 6. The 

vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft across the 

center aisle. The horizontally polarized 36 cm TEM horn antenna was located in the co-pilot’s 

seat and pointed toward the left side of the aircraft. Figure 143 is a time-domain graph of the 

measurement. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

TEM - Setup 6

Figure 143. Main cabin to flight deck TEM horn 

antenna setup 6, time-domain response.

Figure 142. Main cabin to flight deck TEM horn antenna setup 6.
112 

Figure 144 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 7. The 

horizontally polarized 1.2 m TEM horn antenna was placed on the floor in the aisle at the rear of 

the aircraft. The vertically polarized 36 cm TEM horn antenna was located in the co-pilot’s seat 

and pointed toward the left side of the aircraft. Figure 145 is a time-domain graph of the 

measurement. 

 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

TEM - Setup 7

Figure 145. Main cabin to flight deck TEM horn 

antenna setup 7, time-domain response.

Figure 144. Main cabin to flight deck TEM horn antenna setup 7.
113 

Figure 146 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 8, 

measurements 1 and 2. The horizontally polarized 1.2 m TEM horn antenna was placed on the 

floor in the aisle at the rear of the aircraft. The horizontally polarized 36 cm TEM horn antenna 

was located in the co-pilot’s seat and pointed toward the ceiling of the aircraft. Figure 147 is a 

time-domain graph of the measurement and a repeat measurement for the flight deck. 

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

TEM - Setup 8

TEM - Setup 8 - repeat

Figure 147. Main cabin to flight deck TEM horn 

antenna setup 8, time-domain response.

Figure 146. Main cabin to flight deck TEM horn antenna setup 8.
114 

Figure 148 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the flight deck for setup 9. The 

horizontally polarized 1.2 m TEM horn antenna was placed facing into the floor in the aisle at 

the rear of the aircraft. The 36 cm TEM horn antenna was located in the pilot’s seat and pointed 

upward toward the ceiling. Figure 149 is a time-domain graph of the measurement. 

Figure 148. Main cabin to flight deck TEM horn antenna 

setup 9 and setup 10. The 1.2 m TEM horn antenna was in 

the horizontal polarization for setup 9 and in the vertical 

polarization for setup 10.

0 100 200 300

Time (ns)

-0.001

-0.0005

0

0.0005

0.001

Normalized Signal Amplitude

Main Cabin to

Flight Deck

TEM - Setup 9

TEM - Setup 10

Figure 149. Main cabin to flight deck TEM horn antenna 

setup 9 and setup 10, time-domain response.
115 

Figure 150 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 7 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 8 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2

statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

148, Figure 149, and Figure 150. 

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Setup 5 Setup 6 Setup 7

Setup 8 -

Meas 1

Setup 8 -

Meas 2 Setup 9 Setup 10

Figure 150. Whisker-box plots for the TEM horn antennas for main cabin to flight deck insertion loss.
116 

Setup 5 Setup 6 Setup 7 Setup 8 

meas 1

Setup 8

meas 2 Setup 9 Setup 10

WhiskerBox Plot 

Mean 

(dB)

− 62.60 − 62.22 − 67.16 − 62.26 − 62.15 − 71.29 − 67.83

Χ2 Mean 

(dB) − 60.00 − 57.00 − 63.00 − 62.00 − 60.00 − 71.00 − 69.00

 (dB) − 2.00 − 5.00 − 4.00 > − 1.00 − 2.00 > − 1.00 + 2.00

Setup 5 Setup 6 Setup 7 Setup 8 

meas 1

Setup 8

meas 2 Setup 9 Setup 10

WhiskerBox Plot 

Mean 

(dB)

− 62.60 − 62.22 − 67.16 − 62.26 − 62.15 − 71.29 − 67.83

Χ2 Mean 

(dB) − 60.00 − 57.00 − 63.00 − 62.00 − 60.00 − 71.00 − 69.00

 (dB) − 2.00 − 5.00 − 4.00 > − 1.00 − 2.00 > − 1.00 + 2.00

Table 8. TEM horn antenna internal cabin Χ2 - distribution statistics for measurements from the main 

cabin to the flight deck. 

Setup 5 Setup 6 Setup 7 Setup 8 

meas 1

Setup 8

meas 2 Setup 9 Setup 10

Mean 

(dB) −62.60 −62.22 −67.16 −62.26 −62.15 −71.29 −67.83

Median 

(dB) −62.12 −61.94 −67.22 −62.13 −61.45 −70.40 −66.61

Standard 

Deviation 

(dB)

5.36 4.74 6.06 4.61 5.36 4.92 4.89

Minimum 

(dB) −84.56 −83.75 −90.19 −80.67 −78.64 −93.48 −85.75

Maximum 

(dB) −52.30 −54.00 −55.35 −53.65 −51.72 −64.00 −60.19

Setup 5 Setup 6 Setup 7 Setup 8 

meas 1

Setup 8

meas 2 Setup 9 Setup 10

Mean 

(dB) −62.60 −62.22 −67.16 −62.26 −62.15 −71.29 −67.83

Median 

(dB) −62.12 −61.94 −67.22 −62.13 −61.45 −70.40 −66.61

Standard 

Deviation 

(dB)

5.36 4.74 6.06 4.61 5.36 4.92 4.89

Minimum 

(dB) −84.56 −83.75 −90.19 −80.67 −78.64 −93.48 −85.75

Maximum 

(dB) −52.30 −54.00 −55.35 −53.65 −51.72 −64.00 −60.19

Table 7. TEM horn internal cabin statistics for measurements from the main cabin to the flight deck. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.
117 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 5

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 5

Figure 151. Chi-squared plots for TEM horn antenna, setup 5, setup 6, and setup 7, for the main cabin to flight deck insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 6

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 6

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 7

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 7
118 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 8

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 8

Figure 152. Chi-squared plots for TEM horn antenna, setup 8, measurements 1 and 2, and setup 9, for the main cabin to 

flight deck insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 8 - m2

-90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 8 - m2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 9

-100 -90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 9
119 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Flight Deck

Setup 10

-100 -90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Flight Deck

Setup 10

Figure 153. Statistical analysis for TEM horn antenna, setup 10, 

for main cabin to flight deck insertion loss.
120 

6.4.3 Main Cabin to Cargo Bay 

The DRG and TEM horn antennas were measured at various positions between the main cabin 

and cargo bay. An RF cable was run from the VNA in the main cabin through a hole drilled into 

the floor of the main passenger cabin into the cargo bay. In general, for each compartment-tocompartment measurement we tried to position them in approximately the same position for each 

of these runs. 

6.4.3.1 Combined DRG horn antenna positions 

Four positions were measured for the DRG antenna type. No repeat measurements were 

completed in this compartment-to-compartment measurement. Figure 154 shows all 

measurement results for the DRG horn antenna showing a maximum insertion loss of around 

−30 dB and minimum insertion loss of around −55 dB. Figure 155 shows the results for the 

measurement having maximum cabin insertion loss, minimum insertion loss and two system 

noise-floor measurements. The noise-floor measurement shown by the brown trace was the 

system noise floor taken by putting a 50 ohm load on the receiving side of the system. The green 

trace is the ambient noise floor taken by putting the 50 ohm load on the transmitting side and 

looking for the ambient signals that enter the receiving antenna. Both results were averaged by 

se of a 200 MHz bandwidth. 

Whisker-box plots are shown in Figure 156 for the following center frequencies, (1) 100 MHz, 

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these 

plots are from a 200 MHz bandwidth around each center frequency. The plots show the median 

insertion loss for these frequencies range from about −41 dB to −48 dB. The maximum value for 

these frequencies is approximately −26 dB in a 200 MHz bandwidth around a center frequency 

of 1000 MHz, and the minimum insertion loss is −89 dB in a 200 MHz bandwidth around a 

center frequency of 900 MHz. 
121 

The χ

2

 pdf for all DRG horn antenna measurements is shown in Figure 157 and the χ

2

 cdf for all 

DRG horn antenna measurements is shown in Figure 158. The histogram in Figure 157 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Setup 5

DRG - Setup 6

Figure 154. Main cabin to cargo bay DRG antenna insertion loss 

data at each of the four positions.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Setup 5

DRG - Setup 6

Figure 154. Main cabin to cargo bay DRG antenna insertion loss 

data at each of the four positions.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Ambient NOISE Floor

DRG - System NOISE Floor

Figure 155. Main cabin to cargo bay DRG antenna data for the 

maximum insertion loss, the minimum insertion loss, and two noise 

measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Ambient NOISE Floor

DRG - System NOISE Floor

Figure 155. Main cabin to cargo bay DRG antenna data for the 

maximum insertion loss, the minimum insertion loss, and two noise 

measurements.
122 

theoretical average value is around −39 dB. Figure 158 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. This plot shows that the data do not 

tightly follow the theoretical cumulative distribution function. This does not typically seem to be 

the case for the individual positions. 

Figure 156. Whisker-box plots of all main cabin to cargo bay insertion loss measurements 

for the DRG horn antennas at several frequencies. 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

Number of Bins

DRG

Main Cabin to Cargo Bay

(all setups)

Figure 157. Chi-squared probability density function for all 

measurements of insertion loss in the main cabin to cargo bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

Number of Bins

DRG

Main Cabin to Cargo Bay

(all setups)

Figure 157. Chi-squared probability density function for all 

measurements of insertion loss in the main cabin to cargo bay.
123 

6.4.3.2 Individual DRG horn antenna measurement positions 

In this section each measurement position from the main cabin to the cargo bay is individually 

analyzed. Figures 159 to 166 show a photograph of the locations of the antennas in the flight 

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that 

indicates where the antennas were placed. 

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

(all setups)

Figure 158. Chi-squared cumulative density function for all 

measurements of insertion loss in the main cabin to cargo bay.

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

(all setups)

Figure 158. Chi-squared cumulative density function for all 

measurements of insertion loss in the main cabin to cargo bay.
124 

Figure 159 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the cargo bay for setup 1. One vertically polarized antenna 

was located in the rear of the aircraft on top of the seats of the main passenger and pointed 

toward the front of the aircraft. The other vertically polarized antenna was located on an 

insulated cooler and pointed toward the avionics bay. Figure 160 is a time-domain graph of the 

measurement for the cargo bay. 

Cargo

Figure 159. Main cabin to cargo bay DRG horn antenna setup 1. Bay

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

DRG - Setup 1

Figure 160. Main cabin to cargo bay DRG horn 

antenna setup 1, time-domain response.
125 

Figure 161 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the cargo bay for setup 2. One vertically polarized antenna 

was located in the in the first-class section on top of the seats of the main passenger cabin and 

pointed toward the front of the aircraft. The other, vertically polarized, antenna was located on 

an insulated cooler and pointed toward the avionics bay. Figure 162 is a time-domain graph of 

the measurement for the cargo bay.

Cargo

Bay

Figure 161. Main cabin to cargo bay DRG horn antenna setup 2.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

DRG - Setup 2

Figure 162. Main cabin to cargo bay DRG horn 

antenna setup 2, time-domain response.
126 

Figure 163 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the cargo bay for setup 5. One vertically polarized antenna 

was located in the in the first class section on top of the seats of the main passenger cabin and 

pointed toward the front of the aircraft. The other horizontally polarized antenna was located on 

an insulated cooler and pointed toward the avionics bay. Figure 164 is a time-domain graph of 

the measurement for the cargo bay. 

Cargo

Bay

Figure 163. Main cabin to cargo bay DRG horn antenna setup 5.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

DRG - Setup 5

Figure 164. Main cabin to cargo bay DRG horn 

antenna setup 5, time-domain response.
127 

Figure 165 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the cargo bay for setup 6. One vertically polarized antenna 

was located in the rear of the aircraft on top of the seats of the main passenger cabin and pointed 

toward the front of the aircraft. The other, horizontally polarized, antenna was located on an 

insulated cooler pointing toward the avionics bay. A time-domain graph of the measurement for 

the cargo bay is shown in Figure 166. 

Cargo

Figure 165. Main cabin to cargo bay DRG horn antenna setup 6. Bay

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

DRG - Setup 6

Figure 166. Main cabin to cargo bay DRG horn 

antenna setup 6, time-domain response.
128 

Figure 167 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 9 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 10 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2

statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

168 and Figure 169. 

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Setup 1 Setup 2 Setup 5 Setup 6

Figure 167. Whisker-box plots for the DRG horn antennas for main cabin to cargo bay insertion loss.
129 

Setup 1 Setup 2 Setup 5 Setup 6

Mean (dB) − 48.06 − 39.46 − 40.68 − 48.83

Median (dB) − 47.31 − 38.62 − 38.71 − 47.45

Standard 

Deviation (dB) 4.10 7.13 6.01 7.20

Minimum (dB) − 74.68 − 77.41 − 73.48 − 78.66

Maximum (dB) − 41.62 − 26.80 − 34.17 − 38.63

Setup 1 Setup 2 Setup 5 Setup 6

Mean (dB) − 48.06 − 39.46 − 40.68 − 48.83

Median (dB) − 47.31 − 38.62 − 38.71 − 47.45

Standard 

Deviation (dB) 4.10 7.13 6.01 7.20

Minimum (dB) − 74.68 − 77.41 − 73.48 − 78.66

Maximum (dB) − 41.62 − 26.80 − 34.17 − 38.63

Table 9. DRG Horn internal cabin statistics for measurements from the main cabin to the cargo bay. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Table 10. DRG horn antenna internal cabin Χ2 - distribution statistics for measurements 

from the main cabin to the cargo bay.

Setup 1 Setup 2 Setup 5 Setup 6

Whisker-Box Plot 

Mean (dB) − 48.06 − 39.46 − 40.68 − 48.83

Χ2 Mean (dB) − 45.00 − 35.00 − 38.00 − 45.00

 (dB) − 3.00 − 4.00 − 1.00 − 3.00

Setup 1 Setup 2 Setup 5 Setup 6

Whisker-Box Plot 

Mean (dB) − 48.06 − 39.46 − 40.68 − 48.83

Χ2 Mean (dB) − 45.00 − 35.00 − 38.00 − 45.00

 (dB) − 3.00 − 4.00 − 1.00 − 3.00
130 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 1

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 1

Figure 168. Statistical analysis for DRG horn antenna, setup 1, setup 2, and setup 5 for main cabin to cargo bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 2

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 5

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 5

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 1

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 1

Figure 168. Statistical analysis for DRG horn antenna, setup 1, setup 2, and setup 5 for main cabin to cargo bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 2

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 5

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 5
131 

-80 -70 -60 -50 -40 -30 -20 -10 0 Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 6

-80 -60 -40 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Cargo Bay

Setup 6

Figure 169. Statistical analysis for DRG horn antenna, setup 6, 

for main cabin to cargo bay insertion loss.
132 

6.4.3.3 Combined TEM horn antenna positions 

Six positions were measured for the TEM horn antenna. Figure 170 show results for all 

measurements in the main cabin for the TEM horn antenna showing a maximum insertion loss of 

around −35 dB and a minimum insertion loss of around −60 dB. Figure 171 shows a 

measurement of the maximum cabin insertion loss, the minimum insertion loss, and two system 

noise floors. 

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz, 

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions, as shown in 

Figure 172. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a 

total of 2247 points will be in the statistical bandwidth. These plots show the average insertion 

loss for these frequencies range from about −45 dB to −90 dB. The maximum insertion loss for 

these frequencies is approximately −35 dB in a 200 MHz bandwidth around center frequencies of 

1000 and 2000 MHz, and the minimum insertion loss is −135 dB in a 200 MHz bandwidth 

around a center frequency of 100 MHz. 

The χ

2

 pdf for all TEM horn antenna measurements is shown in Figure 173, and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 174. The histogram in Figure 173 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −46 dB. Figure 174 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 
133 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

TEM - Setup 1

TEM - Setup 2

TEM - Setup 3

TEM - Setup 4

TEM - Setup 5

TEM - Setup 6

Figure 170. Main cabin to cargo bay TEM antenna insertion loss 

data at each of the six positions.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

TEM - Setup 1

TEM - Setup 2

TEM - Setup 3

TEM - Setup 4

TEM - Setup 5

TEM - Setup 6

Figure 170. Main cabin to cargo bay TEM antenna insertion loss 

data at each of the six positions.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

TEM - Setup 1

TEM - Setup 4

TEM - System NOISE Floor

Figure 171. Main cabin to cargo bay TEM antenna data for the maximum 

insertion loss, the minimumt insertion loss, and a noise measurement.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Cargo Bay 

TEM - Setup 1

TEM - Setup 4

TEM - System NOISE Floor

Figure 171. Main cabin to cargo bay TEM antenna data for the maximum 

insertion loss, the minimumt insertion loss, and a noise measurement.
134 

Figure 172. Whisker-box plots of all main cabin to cargo bay insertion-loss measurements 

for the TEM horn antennas at several frequencies. 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

20

40

60

80

100

Number of Bins

TEM

Main Cabin to Cargo Bay

(all setups)

Figure 173. Chi-squared probability density function for all 

measurements of insertion loss in the main cabin to cargo bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

20

40

60

80

100

Number of Bins

TEM

Main Cabin to Cargo Bay

(all setups)

Figure 173. Chi-squared probability density function for all 

measurements of insertion loss in the main cabin to cargo bay.
135 

6.4.3.4 Individual TEM horn antenna positions 

A photograph for each TEM antenna measurement location from the main cabin to the cargo 

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside 

the aircraft is shown from Figure 175 to Figure 186. 

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

(all setups)

Figure 174. Chi-squared cumulative density function for all 

measurements of insertion loss in the main cabin to cargo bay.

-80 -70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

(all setups)

Figure 174. Chi-squared cumulative density function for all 

measurements of insertion loss in the main cabin to cargo bay.
136 

Figure 175 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 1, 

measurements 1 and 2. The vertically polarized 1.2 m TEM horn antenna was located in the rear 

of the aircraft positioned across the seats, and pointed toward the front of the aircraft and out the 

windows. The vertically polarized 36 cm TEM horn antenna was located on an insulated cooler 

and pointed toward the avionics bay. A time-domain graph is shown in Figure 176. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 1

Figure 176. Main cabin to cargo bay TEM horn 

antenna setup 1, time-domain response.

Figure 175. Main cabin to cargo bay TEM horn antenna setup 1. Cargo

Bay
137 

Figure 177 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 2. The 

vertically polarized 1.2 m TEM horn antenna was located in the first-class section of the aircraft 

positioned across the seats, and pointed toward the front of the aircraft. The vertically polarized 

36 cm TEM horn antenna was located on an insulated cooler and pointed toward the avionics 

bay. A time-domain graph is shown in Figures 178. 

Cargo

Bay

Figure 177. Main cabin to cargo bay TEM horn antenna setup 2.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 2

Figure 178. Main cabin to cargo bay TEM horn 

antenna setup 2, time-domain response.
138 

Figure 179 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 3. The 

vertically polarized 1.2 m TEM horn antenna was located in the first-class section of the aircraft 

and pointed down into the cargo bay. This was to see whether there was strong coupling with a 

directed measurement. The vertically polarized 36 cm TEM horn antenna was located on an 

insulated cooler and pointed toward the avionics bay. A time-domain graph is shown in Figure 

180. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 3

Figure 180. Main cabin to cargo bay TEM horn 

antenna setup 3, time-domain response.

Figure 179. Main cabin to cargo bay TEM horn antenna setup 3.

Cargo

Bay
139 

Figure 181 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 4. The 

vertically polarized 1.2 m TEM horn antenna was located in the first-class section of the aircraft 

and pointed down into the cargo bay. This was to see whether there was strong coupling with a 

directed measurement. The horizontally polarized 36 cm TEM horn antenna was located on an 

insulated cooler and pointed toward the avionics bay. A time-domain graph is shown in Figure 

182. 

Cargo

Bay

Figure 181. Main cabin to cargo bay TEM horn antenna setup 4.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 4

Figure 182. Main cabin to cargo bay TEM horn 

antenna setup 4, time-domain response.
140 

Figure 183 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 5. The 

horizontally polarized 1.2 m TEM horn antenna was located in the first-class section of the 

aircraft and pointed down into the cargo bay. The horizontally polarized 36 cm TEM horn 

antenna was located on an insulated cooler and pointed toward the avionics bay. A time-domain 

graph is shown in Figure 184. 

Cargo

Bay

Figure 183. Main cabin to cargo bay TEM horn antenna setup 5.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 5

Figure 184. Main cabin to cargo bay TEM horn 

antenna setup 5, time-domain response.
141 

Figure 185 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the cargo bay for setup 6. The 

vertically polarized 1.2 m TEM horn antenna was located in the rear of the aircraft positioned 

across the seats, and pointed toward the front of the aircraft and out the windows. The 

horizontally polarized 36 cm TEM horn antenna was located on an insulated cooler and pointed 

toward the avionics bay. A time-domain graph is shown in Figure 186. 

Cargo

Bay

Figure 185. Main cabin to cargo bay TEM horn antenna setup 6.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Cargo Bay 

TEM - Setup 6

Figure 186. Main cabin to cargo bay TEM horn 

antenna setup 6, time-domain response.
142 

Figure 187 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 11 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 12 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2 statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

188, Figure 189, and Figure 190. 

Figure 187. Whisker-box plots for the TEM horn antennas for main cabin to cargo bay insertion 

loss for individual setups.

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 1 

- Meas 1

Setup 1 

- Repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6
143 

Setup 1 Setup 1

repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

Whisker-Box 

Plot Mean 

(dB)

− 56.03 − 56.17 − 46.94 − 43.05 − 47.12 − 40.68 − 53.88

Χ2 Mean (dB) − 51.00 − 45.00 − 36.00 − 44.00 − 50.00 − 38.00 − 54.00

 (dB) −5.00 −11.00 −11.00 + 1.00 + 3.00 −3.00 < 1.00

Setup 1 Setup 1

repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

Whisker-Box 

Plot Mean 

(dB)

− 56.03 − 56.17 − 46.94 − 43.05 − 47.12 − 40.68 − 53.88

Χ2 Mean (dB) − 51.00 − 45.00 − 36.00 − 44.00 − 50.00 − 38.00 − 54.00

 (dB) −5.00 −11.00 −11.00 + 1.00 + 3.00 −3.00 < 1.00

Table 12. TEM horn antenna internal cabin Χ2 - distribution statistics for measurements from the 

main cabin to the cargo bay. 

Setup 1 Setup 1

repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

Mean (dB) − 56.03 − 56.17 − 46.94 − 43.05 − 47.12 − 40.68 − 53.88

Median (dB) − 54.99 − 55.47 − 45.88 − 41.45 − 46.52 − 38.71 − 52.80

Standard 

Deviation (dB) 6.78 5.55 6.41 5.22 6.01 6.01 6.04

Minimum (dB) − 81.06 − 82.68 − 73.65 − 66.62 − 75.27 − 73.48 − 78.61

Maximum (dB) − 44.43 − 45.74 − 37.02 − 34.91 − 36.68 − 34.17 − 44.39

Setup 1 Setup 1

repeat Setup 2 Setup 3 Setup 4 Setup 5 Setup 6

Mean (dB) − 56.03 − 56.17 − 46.94 − 43.05 − 47.12 − 40.68 − 53.88

Median (dB) − 54.99 − 55.47 − 45.88 − 41.45 − 46.52 − 38.71 − 52.80

Standard 

Deviation (dB) 6.78 5.55 6.41 5.22 6.01 6.01 6.04

Minimum (dB) − 81.06 − 82.68 − 73.65 − 66.62 − 75.27 − 73.48 − 78.61

Maximum (dB) − 44.43 − 45.74 − 37.02 − 34.91 − 36.68 − 34.17 − 44.39

Table 11. TEM Horn internal cabin statistics for measurements from the main cabin to the cargo bay. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.
144 

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 1_redo

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 1_redo

Figure 188. Statistical analysis for TEM horn antenna, setup 1 and a repeat measurement for setup 1, and setup 2 for main cabin to cargo bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 1

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Cargo Bay

Setup 2

-60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 2
145 

Figure 189. Statistical analysis for TEM horn antenna, setup 3, setup 4, and setup 5 for main cabin to cargo bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 3

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 4

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 5

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 5

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 4

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 3
146 

Figure 190. Statistical analysis for TEM horn antenna, setup 6, 

for main cabin to cargo bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Cargo Bay

Setup 6

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Cargo Bay

Setup 6
147 

6.4.4 Main Cabin to Avionics Bay 

The DRG and TEM horn antennas were measured at various positions between the main cabin 

and cargo bay. An RF cable was run from the main passenger cabin through the hole in the floor 

of the main passenger cabin and through a hole in the wall from the cargo bay to the avionics 

bay. In general, for each compartment-to-compartment measurement we tried to position the 

antennas in approximately the same position for each of these runs. 

6.4.4.1 Combined DRG horn antenna positions 

Four positions were measured for the DRG antenna type. No repeat measurements were 

completed in this compartment-to-compartment measurement. Figure 191 shows all 

measurement results for the DRG horn antenna showing a maximum insertion loss of around 

−30 dB and and minimum insertion loss of around −55 dB. Figure 192 shows the results for the 

measurement having maximum cabin insertion loss, minimum insertion loss and two system 

noise-floor measurements. The noise-floor measurement was averaged by use of a 200 MHz 

bandwidth. 

Whisker-box plots are shown in Figure 193 for the following center frequencies, (1) 100 MHz, 

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these 

plots are from a 200 MHz bandwidth around each center frequency. The plots show the median 

insertion loss for these frequencies have values from about −55 dB to −59 dB. The maximum 

value for these frequencies is approximately −32 dB in a 200 MHz bandwidth around center 

frequencies of 1000 MHz and 1500 MHz, and the minimum insertion loss is −98 dB in a 

200 MHz bandwidth around center frequencies of 1500 MHz and 2500 MHz. 
148 

The χ

2

 pdf for all DRG horn antenna measurements is shown in Figure 194 and the χ

2

 cdf for all 

DRG horn antenna measurements is shown in Figure 195. The histogram in Figure 194 contains 

all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −39 dB. Figure 195 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. This plot shows that the data do not 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Setup 3

DRG - Setup 4

Figure 191. Main cabin to avionics bay DRG antenna insertion loss 

data at each of the four positions.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay 

DRG - Setup 1

DRG - Setup 2

DRG - Setup 3

DRG - Setup 4

Figure 191. Main cabin to avionics bay DRG antenna insertion loss 

data at each of the four positions.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

DRG - Setup 4

DRG - Setup 2

DRG - NOISE Floor

 (Cargo Bay to Avionics Bay)

Figure 192. Main cabin to avionics bay DRG horn antenna 

data for the maximum insertion loss, the minimum insertion 

loss, and two noise measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

DRG - Setup 4

DRG - Setup 2

DRG - NOISE Floor

 (Cargo Bay to Avionics Bay)

Figure 192. Main cabin to avionics bay DRG horn antenna 

data for the maximum insertion loss, the minimum insertion 

loss, and two noise measurements.
149 

tightly follow the theoretical cumulative distribution function. This does not typically seem to be 

the case for the individual positions. 

Figure 193. Whisker-box plots of all main cabin to avionics bay insertion loss 

measurements for the DRG horn antennas at several frequencies. 

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

900 MHz

Group 2 -

1 GHz

Group 3 -

1.5 GHz

Group 4 -

2 GHz

Group 5 -

2.5 GHz

Figure 193. Whisker-box plots of all main cabin to avionics bay insertion loss 

measurements for the DRG horn antennas at several frequencies. 

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

900 MHz

Group 2 -

1 GHz

Group 3 -

1.5 GHz

Group 4 -

2 GHz

Group 5 -

2.5 GHz

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

Number of Bins

DRG

Main Cabin to Avionics Bay

(all setups)

Figure 194. Chi-squared probability density function for all DRG 

measurements of insertion loss in the main cabin to avionics bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

Number of Bins

DRG

Main Cabin to Avionics Bay

(all setups)

Figure 194. Chi-squared probability density function for all DRG 

measurements of insertion loss in the main cabin to avionics bay.
150 

6.4.4.2 Individual DRG horn antenna measurement positions 

In this section each measurement position from the main cabin to the avionics bay is individually 

analyzed. Figures 196 to 203 show a photograph of the locations of the antennas in the flight 

deck and the main cabin, a time-domain plot, and a schematic of the inside of the 737-200 that 

indicates where the antennas were placed. 

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

(all setups)

Figure 195. Chi-squared cumulative density function for all DRG 

measurements of insertion loss in the main cabin to avionics bay.

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

(all setups)

Figure 195. Chi-squared cumulative density function for all DRG 

measurements of insertion loss in the main cabin to avionics bay.
151 

Figure 196 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the avionics bay for setup 1, measurements with the 

avionics bay door open and closed. One vertically polarized antenna was located in the rear of 

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the 

aircraft. The other vertically polarized antenna was located on an insulated cooler and pointed 

toward the front of the aircraft. A time-domain graph of the measurement for the cargo bay is 

shown in Figure 197. 

Avionics

Bay

Figure 196. Main cabin to avionics bay DRG horn antenna setup 1.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

DRG - Setup 1

Figure 197. Main cabin to avionics bay DRG horn 

antenna setup 1, time-domain response.
152 

Figure 198 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the avionics bay for setup 2, measurements with the 

avionics bay door open and closed. One vertically polarized antenna was located in the rear of 

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the 

aircraft. The horizontally polarized other antenna was located on an insulated cooler and pointed 

toward the front of the aircraft. A time-domain graph of the measurement for the cargo bay is 

shown in Figure 199.

Avionics

Bay

Figure 198. Main cabin to avionics bay DRG horn antenna setup 2.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

DRG - Setup 2

Figure 199. Main cabin to avionics bay DRG horn 

antenna setup 2, time-domain response.
153 

Figure 200 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the avionics bay for setup 3, measurements with the 

avionics bay door open and closed. One vertically polarized antenna was located in the rear of 

the aircraft on top of the seats of the main passenger cabin and pointed toward the front of the 

aircraft. The other antenna was located on an insulated cooler and pointed upward toward 

avionics bay door. A time-domain graph of the measurement for the cargo bay is shown in 

Figure 201.

Figure 200. Main cabin to avionics bay DRG horn antenna setup 3.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

DRG - Setup 3

Figure 201. Main cabin to avionics bay DRG horn 

antenna setup 3, time-domain response.

Avionics

Bay
154 

Figure 202 shows the placement of a transmitting DRG horn antenna in the main passenger cabin 

and a receiving DRG horn antenna in the avionics bay for setup 4, measurements with the 

avionics bay door open and closed. One horizontally polarized antenna was located in the first 

class section on top of the main passenger seats. The antenna pointed toward the front of the 

aircraft. The other antenna was located on an insulated cooler and pointed upward toward 

avionics bay door. A time-domain graph of the measurement for the cargo bay is shown in 

Figure 203. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

DRG - Setup 4

Figure 203. Main cabin to avionics bay DRG horn 

antenna setup 4, time-domain response.

Avionics

Bay Figure 202. Main cabin to avionics bay DRG horn antenna setup 4.
155 

Figure 204 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 13 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 14 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2 statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

202. 

Figure 204. Statistical analysis for DRG horn antenna for main cabin to avionics bay 

insertion loss for individual setups.

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 1 Setup 2 Setup 3 Setup 4
156 

Setup 1 Setup 2 Setup 3 Setup 4

Mean (dB) − 59.00 − 60.41 − 56.53 − 42.89

Median (dB) − 57.86 − 59.25 − 55.37 − 41.51

Standard 

Deviation (dB) 5.16 5.78 5.23 6.43

Minimum (dB) − 80.88 − 92.70 − 75.04 − 69.71

Maximum (dB) − 51.04 − 53.00 − 48.70 − 33.68

Setup 1 Setup 2 Setup 3 Setup 4

Mean (dB) − 59.00 − 60.41 − 56.53 − 42.89

Median (dB) − 57.86 − 59.25 − 55.37 − 41.51

Standard 

Deviation (dB) 5.16 5.78 5.23 6.43

Minimum (dB) − 80.88 − 92.70 − 75.04 − 69.71

Maximum (dB) − 51.04 − 53.00 − 48.70 − 33.68

Table 13. DRG Horn internal cabin statistics for measurements from the main cabin to the avionics bay. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.

Setup 1 Setup 2 Setup 3 Setup 4

Whisker-Box 

Plot Mean (dB) − 59.00 − 60.41 − 56.53 − 42.89

Χ2 Mean (dB) − 62.00 − 57.00 − 52.00 − 37.00

 (dB) + 3.00 − 3.00 − 4.00 − 6.00

Setup 1 Setup 2 Setup 3 Setup 4

Whisker-Box 

Plot Mean (dB) − 59.00 − 60.41 − 56.53 − 42.89

Χ2 Mean (dB) − 62.00 − 57.00 − 52.00 − 37.00

 (dB) + 3.00 − 3.00 − 4.00 − 6.00

Table 14. DRG horn antenna internal cabin Χ2 - distribution statistics for measurements 

from the main cabin to the avionics bay. 
157 

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

Setup 2

Figure 205. Statistical analysis for DRG horn antenna, for setup1, setup 2, setup 3, and setup 4 for main cabin to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Avionics Bay

Setup 2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Avionics Bay

Setup 1

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

Setup 1

-70 -60 -50 -40 -30 -20

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

Setup 4

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Main Cabin to Avionics Bay

Setup 4

-70 -60 -50 -40 -30 -20 -10

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Main Cabin to Avionics Bay

Setup 3

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Main Cabin to Avionics Bay

Setup 3
158 

6.4.4.3 Combined TEM horn antenna positions 

Three positions were measured for the TEM horn antenna type. Figure 206 shows results for all 

measurement results in the main cabin for the TEM horn antenna showing a maximum insertion 

loss of around −35 dB and a minimum insertion loss of around −60 dB. Figure 207 show results 

for the maximum cabin insertion loss measurement, the minimum insertion loss measurement, 

and a system noise floor taken from the cargo bay to the avionics bay. 

For the TEM horn antennas, statistics are given for a 200 MHz bandwidth around 900 MHz, 

1000 MHz, 1500 MHz, 2000 MHz, and 2500 MHz over all measurement positions as shown in 

Figure 208. In a 200 MHz bandwidth there are 321 points, so for six measurement positions a 

total of 2247 points will be in the statistical bandwidth. The maximum insertion loss for these 

frequencies is approximately −41 dB in a 200 MHz bandwidth around a center frequency of 

1000 MHz, and the minimum insertion loss is −156 dB in a 200 MHz bandwidth around a center 

frequency of 100 MHz. 

The χ

2

 pdf for all TEM horn antenna measurements is shown in Figure 20, and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 210. The histogram in Figure 209 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −46 dB. Figure 210 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 
159 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

TEM - Setup 1 (Avionics door open)

TEM - Setup 1 (door closed)

TEM - Setup 4

TEM - Setup 5 (meas 1)

TEM - Setup 5 (meas 2)

Figure 206. Main cabin to avionics bay TEM antenna insertion loss 

data at each of the three positions, with two additional 

measurements.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

-30

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

TEM - Setup 1 (Avionics door open)

TEM - Setup 1 (door closed)

TEM - Setup 4

TEM - Setup 5 (meas 1)

TEM - Setup 5 (meas 2)

Figure 206. Main cabin to avionics bay TEM antenna insertion loss 

data at each of the three positions, with two additional 

measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

TEM - Setup 4

TEM - Setup 1 (door closed)

TEM - NOISE Floor

 (Cargo Bay to Avionics Bay)

Figure 207. Main cabin to avionics bay TEM horn antenna 

data for the maximum insertion loss, the minimum insertion 

loss, and two noise measurements.

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Main Cabin to 

Avionics Bay

TEM - Setup 4

TEM - Setup 1 (door closed)

TEM - NOISE Floor

 (Cargo Bay to Avionics Bay)

Figure 207. Main cabin to avionics bay TEM horn antenna 

data for the maximum insertion loss, the minimum insertion 

loss, and two noise measurements.
160 

-180.00

-160.00

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

100 MHz

Group 2 -

500 MHz

Group 3 - 1

GHz

Group 4 - 1.5

GHz

Group 5 - 2

GHz

Group 6 - 2.5

GHz

Figure 208. Whisker-box plots of all main cabin to avionics bay insertion loss measurements 

for the TEM horn antennas at several frequencies. 

-180.00

-160.00

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

100 MHz

Group 2 -

500 MHz

Group 3 - 1

GHz

Group 4 - 1.5

GHz

Group 5 - 2

GHz

Group 6 - 2.5

GHz

Figure 208. Whisker-box plots of all main cabin to avionics bay insertion loss measurements 

for the TEM horn antennas at several frequencies. 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

Number of Bins

TEM

Main Cabin to Avionics Bay

(all setups)

Figure 209. Chi-squared probability density function for all TEM 

measurements of insertion loss in the main cabin to avionics bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

Number of Bins

TEM

Main Cabin to Avionics Bay

(all setups)

Figure 209. Chi-squared probability density function for all TEM 

measurements of insertion loss in the main cabin to avionics bay.
161 

6.4.4.4 Individual TEM horn antenna positions 

A photograph for each TEM antenna measurement location from the main cabin to the cargo 

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside 

the aircraft is shown from Figure 211 to Figure 216. 

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

(all setups)

Figure 210. Chi-squared cumulative density function for all TEM 

measurements of insertion loss in the main cabin to avionics bay.

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

(all setups)

Figure 210. Chi-squared cumulative density function for all TEM 

measurements of insertion loss in the main cabin to avionics bay.
162 

Figure 211 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the avionics bay for setup 1, for 

measurements with the avionics bay door open and closed. The vertically polarized 1.2 m TEM 

horn antenna was located in the rear of the aircraft across the seats and pointed forward toward 

the windows. The vertically polarized 36 cm TEM horn antenna was located on an insulated 

cooler and pointed toward the front of the aircraft. A time-domain graph of the measurement is 

shown in Figure 212. 

Avionics

Bay

Figure 211. Main cabin to avionics bay TEM horn antenna setup 1.

Figure 212. Main cabin to avionics bay TEM horn 

antenna setup 1, time-domain response.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

TEM - Setup 1

 (avionics bay door closed)

TEM - Setup 1

 (avionics bay door open)
163 

Figure 213 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the avionics bay for setup 4. The 

horizontally polarized 1.2 m TEM horn antenna was located in the first-class section on top of 

the main passenger seats. The 36 cm TEM horn antenna was located on an insulated cooler and 

pointed upward toward avionics bay door. A time-domain graph of the measurement is shown in 

Figure 214. 

Figure 213. Main cabin to avionics bay TEM horn antenna setup 4.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

TEM - Setup 4

Figure 214. Main cabin to avionics bay TEM horn 

antenna setup 4, time-domain response.

Avionics

Bay
164 

Figure 215 shows the placement of a transmitting 1.2 m TEM horn antenna in the main 

passenger cabin and a receiving 36 cm TEM horn antenna in the avionics bay for setup 5, 

measurements 1 and 2. The 1.2 m TEM horn antenna was located on the floor in the rear of the 

aircraft and pointed forward down the aisle. The 36 cm TEM horn antenna was located on an 

insulated cooler and pointed upward toward the avionics bay door. A time-domain graph of the 

measurement is shown in Figure 216.

Figure 216. Main cabin to avionics bay TEM horn 

antenna setup 5, time-domain response.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Main Cabin to

Avionics Bay

TEM - Setup 5 (meas 1)

TEM - Setup 5 (meas 2)

Figure 215. Main cabin to avionics bay TEM horn antenna setup 5.

Avionics

Bay
165 

Figure 217 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 15 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 16 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2 statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

218 and Figure 219. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup 1 -

Avionics Bay

door open

Setup 1 -

Avionics Bay

door closed Setup 4

Setup 5 - Meas

1

Setup 5 - Meas

2

Figure 217. Statistical analysis for TEM horn antennas for main cabin to avionics bay insertion 

loss for individual setups.
166 

Setup 1 

Avionics Bay 

door open

Setup 1 

Avionics Bay 

door closed

Setup 4 Setup 5 

meas 1

Setup 5 

meas 2

Whisker-Box Plot 

Mean (dB) − 65.11 − 65.47 − 50.85 − 63.93 − 64.72

Χ2 Mean (dB) − 62.00 − 62.00 − 51.00 − 58.00 − 62.00

 (dB) − 3.00 − 3.00 < 1.00 − 6.00 − 3.00

Table 16. TEM horn antenna internal cabin Χ2 - distribution statistics for measurements from the 

main cabin to the avionics bay. 

Setup 1 

Avionics Bay 

door open

Setup 1 

Avionics Bay 

door closed

Setup 4 Setup 5 

meas 1

Setup 5 

meas 2

Mean (dB) − 65.11 − 65.47 − 50.85 − 63.93 − 64.72

Median (dB) − 64.48 − 64.98 − 49.75 − 63.66 − 64.04

Standard Deviation 

(dB) 3.88 4.86 6.03 5.98 6.11

Minimum (dB) − 80.25 − 85.51 − 69.11 − 90.38 − 83.74

Maximum (dB) − 58.63 − 58.29 − 41.41 − 53.59 − 54.13

Table 15. TEM Horn internal cabin statistics for measurements from the main cabin to the avionics 

bay. The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.
167 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

TEM

Main Cabin to Avionics Bay

Setup 1 (door closed)

-100 -90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

Setup 1 (door closed)

Figure 218. Statistical analysis for TEM horn antenna, setup 1 (avionics bay door open and closed), and setup 4 for main cabin to avionics bay insertion loss.

-90 -80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

)Bd(FDC

TEM

Main Cabin to Avionics Bay

Setup 1 (door open)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

nsiBf oreb umN

TEM

Main Cabin to Avionics Bay

Setup 1 (door open)

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

Setup 4

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Main Cabin to Avionics Bay

Setup 4
168 

Figure 219. Statistical analysis for TEM horn antenna, setup 5-measurement 1 and 2, for 

main cabin to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Avionics Bay

Setup 5 - m1

-90 -80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

Setup 5 - m1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Main Cabin to Avionics Bay

Setup 5 - m2

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Main Cabin to Avionics Bay

Setup 5 - m2
169 

6.4.5 Cargo Bay to Avionics Bay 

The DRG and TEM horn antennas were measured at various positions between the cargo bay 

and the avionics bay. The VNA was placed inside the cargo bay and an RF cable was run from 

the cargo bay to the avionics bay. In general, for each compartment-to-compartment 

measurement we tried to position the antennas in approximately the same position for each of 

these runs. 

6.4.5.1 Combined TEM horn antenna positions 

Three positions were measured for the TEM horn antenna type and three repeat measurements 

were taken at one location. Figure 220 shows the data for the TEM horn antennas for the 

maximum cabin insertion loss and a system noise floor. Typically the noise floor drops when we 

place the antennas in compartments that have fewer leakage paths due to extra shielding that 

occurs from the outside environment. Figure 221 shows maximum insertion loss for the TEM 

horn antennas around −40 dB dropping to a minimum insertion loss of −80 dB. The TEM horn 

antennas were then left in one orientation and were remeasured three times to determine system 

variability as shown in Figure 221. Figure 222 shows the data for three different measurements 

at different orientations in the two compartments. 

Whisker-box plots are shown in Figure 223 for the following center frequencies, (1) 100 MHz, 

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these 

plots are from a 200 MHz bandwidth around each center frequency. The plots show that the 

median insertion loss for these frequencies have values from about −58 dB to −90 dB. The 

maximum value for these frequencies is approximately −50 dB in a 200 MHz bandwidth around 

a center frequency of 1500 MHz, and the minimum insertion loss is −118 dB in a 200 MHz 

bandwidth around center frequencies of 900 MHz. 

The χ

2

 pdf for all DRG horn antenna measurements is shown in Figure 224 and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 225. The histogram in Figure 224 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −57 dB. Figure 225 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 
170 

d

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

TEM - Setup A (meas 1)

TEM - NOISE Floor

Figure 220. Cargo bay to avionics bay TEM antenna data for the 

maximum insertion loss and a system noise measurement.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

TEM - Setup A (meas 1)

TEM - Setup A (meas 2)

TEM - Setup A (meas 3)

Figure 221. Cargo bay to avionics bay TEM horn antenna data insertion 

loss data at each of the three positions.
171 

-140.00

-120.00

-100.00

-80.00

-60.00

-40.00

-20.00

0.00

Group 1 -

100 MHz

Group 2 -

500 MHz

Group 3 -

1 GHz

Group 4 -

1.5 GHz

Group 5 -

2 GHz

Group 6 -

2.5 GHz

Figure 223. Whisker-box plots for all cargo bay to avionics bay insertion loss measurements 

of the TEM horn antennas at several frequencies. 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

TEM - Setup A (meas 1)

TEM - Setup B

TEM - Setup C

Figure 222. Cargo bay to avionics bay TEM horn antenna data insertion 

loss data at one position for three independent measurements.
172 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

Number of Bins

TEM

Cargo Bay to Avionics Bay

(all setups)

Figure 224. Chi-squared probability density function for all TEM 

measurements of insertion loss in the cargo bay to the avionics bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

Number of Bins

TEM

Cargo Bay to Avionics Bay

(all setups)

Figure 224. Chi-squared probability density function for all TEM 

measurements of insertion loss in the cargo bay to the avionics bay.

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

(all setups)

Figure 225. Chi-squared cumulative density function for all TEM 

measurements of insertion loss in the cargo bay to the avionics bay.

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

(all setups)

Figure 225. Chi-squared cumulative density function for all TEM 

measurements of insertion loss in the cargo bay to the avionics bay.
173 

6.4.5.2 Individual TEM horn antenna positions 

Photographs for each TEM antenna measurement location from the main cabin to the cargo bay, 

its associated time-domain waveform, and a schematic showing the antenna positions inside the 

aircraft are shown from Figure 226 to Figure 231. 
174 

Figure 226 shows the placement of a transmitting 1.2 m TEM horn antenna in the cargo bay and 

a receiving 36 cm horn antenna in the avionics bay for setup A, measurements 1, 2, and 3. The 

1.2 m TEM horn antenna was located in the forward section of the cargo bay close to the 

avionics bay propped on a box pointed toward the rear back corner of the cargo bay with a mixed 

polarization. The vertically polarized 36 cm antenna was located on an insulated cooler pointing 

toward the front of the aircraft. A time-domain graph of all three measurements for position A 

for the cargo bay to avionics bay is shown in Figure 227. Traces 2 and 3 were offset, in the 

positive y-direction, from measurement 1 to compare differences between the repeat 

measurements. 

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

TEM - Setup A (meas 1)

TEM - Setup A (meas 2)

TEM - Setup A (meas 3)

Figure 227. Cargo bay to avionics bay TEM horn 

antenna setup A, time-domain response.

Figure 226. Cargo bay to avionics bay TEM horn antenna setup A.

Avionics

Bay

Cargo

Bay
175 

Figure 228 shows the placement of a transmitting 1.2 m TEM horn antenna in the cargo bay and 

a receiving 36 cm TEM horn antenna in the avionics bay for setup B. The 1.2 m antenna was 

located in the forward section of the cargo bay close to the avionics bay and propped above the 

floor on a cargo net pointing toward the main passenger cabin floor. The horizontally polarized 

36 cm antenna was located on the floor in the avionics bay. A time-domain graph of the 

measurement is shown in Figure 229. 

Figure 228. Cargo bay to avionics bay TEM horn antenna setup B.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

TEM - Setup B

Figure 229. Cargo bay to avionics bay TEM 

horn antenna setup B, time-domain response.

Avionics

Bay

Cargo

Bay
176 

Figure 230 shows the placement of a transmitting 1.2 m TEM horn antenna in the cargo bay and 

a receiving 36 cm TEM horn antenna in the avionics bay for setup C. The 1.2 m TEM horn 

antenna was located in the middle part of the cargo bay and pointed toward the avionics bay. 

The 36 cm TEM horn antenna was placed on the floor of the avionics bay and pointed down 

toward the floor. A time-domain graph of the measurement is shown in Figure 231.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

TEM - Setup C

Figure 231. Cargo bay to avionics bay TEM horn 

antenna setup C, time-domain response.

Figure 230. Cargo bay to avionics bay TEM horn antenna setup C.

Avionics

Bay

Cargo

Bay
177 

Figure 232 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 17 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 18 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2

statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

233 and Figure 234. 

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup A -

Meas 1

Setup A -

Meas 2

Setup A -

Meas 3

Setup B -

Meas 1

Setup C -

Meas 1

Figure 232. Statistical analysis for TEM horn antenna, setup A (measurements 1, 2, 3), setup B 

and setup C for cargo bay to avionics bay insertion loss.
178 

Setup A 

meas 1

Setup A

meas 2

Setup A 

meas 3 Setup B Setup C

Whisker-Box Plot 

Mean (dB) − 57.73 − 59.10 − 58.89 − 61.12 − 56.59

Χ2 Mean (dB) − 55.00 − 60.00 − 59.00 − 59.00 − 57.00

 (dB) − 3.00 + 1.00 < 1.00 − 2.00 < 1.00

Table 18. TEM horn antenna internal cabin Χ2-distribution statistics for measurements from the 

cargo bay to the avionics bay. 

Setup A 

meas 1

Setup A

meas 2

Setup A 

meas 3 Setup B Setup C

Mean (dB) − 57.73 − 59.10 − 58.89 − 61.12 − 56.59

Median (dB) − 56.98 − 58.53 − 57.72 − 61.67 − 56.10

Standard Deviation 

(dB) 5.99 4.56 4.66 3.50 4.63

Minimum (dB) − 78.56 − 79.57 − 81.70 − 76.72 − 81.12

Maximum (dB) − 46.97 − 49.85 − 51.22 − 55.94 − 48.84

Table 17. TEM Horn internal cabin statistics for measurements from the cargo bay to the avionics bay. The 

sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz. 
179 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Cargo Bay to Avionics Bay

Setup A (m2)

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

Setup A (m2)

Figure 233. Statistical analysis for TEM horn antenna, setup A (measurements 1, 2, 3), for cargo bay to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

sniBforebmuN

TEM

Cargo Bay to Avionics Bay

Setup A (m1)

-80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

)Bd(FDC

TEM

Cargo Bay to Avionics Bay

Setup A (m1)

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

TEM

Cargo Bay to Avionics Bay

Setup A (m3)

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

Setup A (m3)
180 

-80 -70 -60 -50 -40 -30 -20 -10 0 Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Cargo Bay to Avionics Bay

Setup B

-100 -90 -80 -70 -60 -50

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

Setup B

Figure 234. Statistical analysis for TEM horn antenna, setup B and setup C for cargo bay to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0 Penetration Bin (dB)

0

10

20

30

40

50

Number of Bins

TEM

Cargo Bay to Avionics Bay

Setup C

-90 -80 -70 -60 -50 -40

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

TEM

Cargo Bay to Avionics Bay

Setup C
181 

6.4.5.3 Combined DRG horn antenna positions

Three positions were measured for the DRG antenna and three repeat measurements were taken 

at one location. Figure 235 shows the data for the DRG horn antennas for the maximum cabin 

insertion loss and a system noise floor. Typically the noise floor drops when the antennas were 

placed in compartments that have fewer leakage paths due to extra shielding that occurs from the 

outside environment. Figure 236 shows maximum insertion loss for the DRG horn antennas 

around −45 dB dropping to minimum insertion loss of −65 dB. The DRG horn antennas were 

then left in one orientation and were remeasured three times to determine system variability, as 

shown in Figure 236. Figure 237 shows the data for three different measurements at different 

orientations in the two compartments. 

Whisker-box plots are shown in Figure 238 for the following center frequencies, (1) 100 MHz, 

(2) 500 MHz, (3) 1000 MHz, (4) 1500 MHz, (5) 2000 MHz, and (6) 2500 MHz. Data in these 

plots are from a 200 MHz bandwidth around each center frequency. The plots show that the 

median insertion loss for these frequencies has values from about −50 dB to −55 dB. The 

maximum value for these frequencies is approximately −35 dB in a 200 MHz bandwidth around 

a center frequency of 1500 MHz, and the minimum insertion loss is −93 dB in a 200 MHz 

bandwidth around center frequencies of 900 MHz and 1000 MHz. 

The χ

2

 pdf for all DRG horn antenna measurements is shown in Figure 239 and the χ

2

 cdf for all 

TEM horn antenna measurements is shown in Figure 240. The histogram in Figure 239 consists 

of all points binned into 1 dB bins (light-blue bins) and plotted against the theoretical probability 

density function (dark-blue trace) and the average value of the theoretical data (pink trace). The 

theoretical average value is around −47 dB. Figure 240 is the data (dark-blue, solid trace) plotted 

against the theoretical cumulative distribution function. 

0 1000 2000 3000

Frequency (MHz)

-120

-110

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

DRG - Setup D (meas 1)

DRG - NOISE Floor

Figure 235. Cargo bay to avionics bay DRG antenna data for the 

maximum insertion loss and a system noise measurement.
182 

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

DRG - Setup D (meas 1)

DRG - Setup D (meas 2)

DRG - Setup D (meas 3)

Figure 236. Cargo bay to avionics bay DRG antenna data insertion 

loss data at one position for three independent measurements.

0 1000 2000 3000

Frequency (MHz)

-100

-90

-80

-70

-60

-50

-40

Insertion Loss (dB)

Cargo Bay to 

Avionics Bay

DRG - Setup D (meas 1)

DRG - Setup E

DRG - Setup F

Figure 237. Cargo bay to avionics bay DRG antenna data insertion 

loss data at each of the three positions.
183 

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

200

Number of Bins

DRG

Cargo Bay to Avionics Bay

(all setups)

Figure 239. Chi-squared probability density function for all DRG 

measurements of insertion loss in the cargo bay to the avionics bay.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

40

80

120

160

200

Number of Bins

DRG

Cargo Bay to Avionics Bay

(all setups)

Figure 239. Chi-squared probability density function for all DRG 

measurements of insertion loss in the cargo bay to the avionics bay.

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Group 1 - 900 

MHz

Group 2 - 1

GHz

Group 3 - 1.5

GHz

Group 4 - 2

GHz

Group 5 - 2.5

GHz

Figure 238. Whisker-box plots for all cargo bay to avionics bay insertion loss 

measurements of the DRG horn antennas at several frequencies. 
184 

6.4.5.4 Individual TEM horn antenna positions 

A photograph for each TEM antenna measurement location from the main cabin to the cargo 

bay, its associated time-domain waveform, and a schematic showing the antenna positions inside 

the aircraft is shown from Figure 241 to Figure 246. 

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

(all setups)

Figure 240. Chi-squared cumulative density function for all DRG 

measurements of insertion loss in the cargo bay to the avionics bay.

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.2

0.4

0.6

0.8

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

(all setups)

Figure 240. Chi-squared cumulative density function for all DRG 

measurements of insertion loss in the cargo bay to the avionics bay.
185 

Figure 241 shows the placement of a transmitting DRG horn antenna in the cargo bay and a 

receiving DRG horn antenna in the avionics bay for setup D, measurements 1, 2, and 3. One 

antenna was located in the forward section of the cargo bay close to the avionics bay and 

propped against a box pointed toward the rear back corner of the cargo bay with a mixed 

polarization. The other vertically polarized antenna was located on an insulated cooler pointing 

toward the front of the aircraft. A time-domain graph of all three measurements for position D 

for the cargo bay to avionics bay is shown in Figure 242. Traces 2 and 3 were offset, in the 

positive y-direction, from measurement 1 to compare differences between the repeat 

measurements. 

Figure 242. Cargo bay to avionics bay DRG horn 

antenna setup D, time-domain response.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

DRG - Setup D (meas 1)

DRG - Setup D (meas 2)

DRG - Setup D (meas 3)

Avionics

Bay

Cargo

Bay Figure 241. Cargo bay to avionics bay DRG horn antenna setup D.
186 

Figure 243 shows the placement of a transmitting DRG horn antenna in the cargo bay and a 

receiving DRG horn antenna in the avionics bay for setup E. One antenna was located in the 

forward section of the cargo bay close to the avionics bay propped above the floor on a stack of 

insulation pointing toward the front corner of the cargo bay with a mixed polarization. The other 

antenna was located on an insulated cooler pointing down to the floor of the avionics bay. A 

time-domain graph of the measurement is shown in Figure 244.

Figure 243. Cargo bay to avionics bay DRG horn antenna setup E.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

DRG - Setup E

Figure 244. Cargo bay to avionics bay DRG horn 

antenna setup E, time-domain response.

Avionics

Bay

Cargo

Bay
187 

Figure 245 shows the placement of a transmitting DRG horn antenna in the cargo bay and a 

receiving DRG horn antenna in the avionics bay for setup F, measurements 1 and 2. One 

antenna was located in the middle part of the cargo bay suspended from a support point toward 

the avionics bay. The other antenna was placed on the floor of the avionics bay pointing toward 

the front of the aircraft in a mixed polarization. A time-domain graph of the measurement is 

shown in Figure 246.

0 100 200 300

Time (ns)

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Normalized Signal Amplitude

Cargo Bay to

Avionics Bay

DRG - Setup F

Figure 246. Cargo bay to avionics bay DRG 

horn antenna setup F, time-domain response.

Figure 245. Cargo bay to avionics bay DRG horn antenna setup F.

Avionics

Bay

Cargo

Bay
188 

Figure 247 shows whisker-box plots of each individual setup. The group of data was analyzed 

around a center frequency of 1000 MHz over a 200 MHz bandwidth containing 321 points. 

Table 19 summarizes the statistics of each setup for the whisker-box plots, and includes the mean 

value, the median value, the standard deviation, the maximum value in the group, and the 

minimum value in the group. Table 20 summarizes the differences between the mean value for 

the whisker-box plot analysis and the mean value for the χ

2 statistic. The difference between the 

two means is also displayed. Finally, the χ

2

 pdf and the χ

2

 cdf are plotted for each setup in Figure 

248 and Figure 249. 

-100.00

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

Setup D -

Meas1

Setup D -

Meas2

Setup D -

Meas3

Setup E -

Meas1

Setup F -

Meas1

Setup F -

Meas2

Figure 247. Statistical analysis for DRG horn antenna, setup D (measurements 1, 2, 3), setup 

E ( measurements 1 and 2), and setup F for cargo bay to avionics bay insertion loss.
189 

Setup D 

meas 1

Setup D

meas 2

Setup D 

meas 3 Setup E Setup F 

meas 1

Setup F 

meas 1

Whisker-Box 

Plot Mean (dB) − 50.75 − 50.82 − 50.65 − 48.75 − 50.70 − 50.95

Χ2 Mean (dB) − 49.00 − 51.00 − 50.00 − 47.00 − 53.00 − 49.00

 (dB) − 2.00 < 1.00 < 1.00 − 2.00 + 3.00 − 1.00

Table 20. DRG horn antenna internal cabin Χ2-distribution statistics for measurements from the cargo 

bay to the avionics bay. 

Setup D 

meas 1

Setup D

meas 2

Setup D 

meas 3 Setup E Setup F 

meas 1

Setup F 

meas 1

Mean (dB) − 50.75 − 50.82 − 50.65 − 48.75 − 50.70 − 50.95

Median (dB) − 49.59 − 49.70 − 49.93 − 46.67 − 49.99 − 49.88

Standard 

Deviation (dB) 5.37 6.13 6.41 8.38 4.77 5.46

Minimum (dB) − 70.22 − 80.82 − 79.69 − 92.86 − 65.06 − 75.08

Maximum (dB) − 41.22 − 40.55 − 40.42 − 37.24 − 41.55 − 41.80

Table 19. DRG Horn internal cabin statistics for measurements from the cargo bay to the avionics bay. 

The sample size was 321 points in a 200 MHz bandwidth around a center frequency of 1 GHz.
190 

Figure 248. Statistical analysis for DRG horn antenna, setup D (measurements 1, 2, and 3), for cargo bay to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

nsiBf oreb umN

DRG

Cargo Bay to Avionics Bay

Setup D1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Cargo Bay to Avionics Bay

Setup D2

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Cargo Bay to Avionics Bay

Setup D3

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

Setup D3

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

Setup D2

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

)Bd(FDC

DRG

Cargo Bay to Avionics Bay

Setup D1
191 

Figure 249. Statistical analysis for DRG horn antenna, setup E , and setup F, measurements 1 and 2 for cargo bay to avionics bay insertion loss.

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

5040302010

Number of Bins

DRG

Cargo Bay to Avionics Bay

Setup E1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Cargo Bay to Avionics Bay

Setup F1

-80 -70 -60 -50 -40 -30 -20 -10 0

Penetration Bin (dB)

0

540302010

0

Number of Bins

DRG

Cargo Bay to Avionics Bay

Setup F2

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

Setup F2

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

Setup F1

-80 -70 -60 -50 -40 -30

Penetration Bin (dB)

0

0.80.60.40.2

1

CDF (dB)

DRG

Cargo Bay to Avionics Bay

Setup E1
192 

7. Uncertainty Analysis

The sources of uncertainty are based on NISTIR 5019 [39], which provides a natural framework 

for the identification of source uncertainties encountered in aircraft shielding measurements, 

along with an efficient method for tracking and combining them. 

 

Six sources of measurement uncertainty are considered in our analysis: 

 Measurement Repeatability 

 Range Uncertainties/Distance Correction 

 Time Gating 

 Drift 

 Polarization Mismatch 

 Signal-to-Noise Ratio 

These sources of uncertainties (influence factors) were evaluated as follows: 

1. Measurement Repeatability: For a given internal orientation, we took multiple data sets, in 

which we moved the external antennas to and from the same location. 

 

2. Range Uncertainties: We used estimates of variations when positioning the antennas for both 

the reference and airframe measurements. 

3. Time Gating: We determined time-gating uncertainties by varying the gate width and 

performing a statistical analysis on the resulting amplitude spectra; see Appendix A for further 

discussion. 

4. Drift: The uncertainty due to instrumentation drift was small and was computed by use of the 

data obtained from system calibration checks done before and after circumnavigating the aircraft. 

The uncertainty was determined by calculating the difference and dividing that by the average of 

the two signals. 

5. Polarization Mismatch: Polarization mismatch uncertainties occur because antennas could be 

misaligned for a given polarization. We calculated one uncertainty based on a possible 

misalignment of 5°. The other term comes from the possible leakage from one polarization to 

the other. The cross-polarization of our TEM horn antennas is approximately −20 dB, and for the 

DRG antennas it is approximately −15 dB. These two factors both contribute to the polarization 

mismatch uncertainty. 

6. Signal-to-Noise Ratio: These uncertainties were calculated for the FAA 737-200 aircraft. 

The effect of these six influence factors on the measured penetration is summarized in Table 21. 

This table lists the fractional uncertainties [40, 41] resulting from each influence factor. The 

signal-to-noise uncertainties were not calculated for specific signal-to-noise levels, but were 

determined for measurements that have a signal-to-noise ratio of 60 dB below 9 GHz and 
193 

decreasing to approximately 40 dB at higher frequencies. The most significant errors are due to 

repeatability and time-gating uncertainties below 9 GHz, and above 9 GHz they are due to timegating and extrapolation uncertainties. Signal-to-noise is the next largest uncertainty, followed 

by the range/distance correction uncertainties, polarization mismatch, and drift, respectively. 

The combined standard uncertainty was computed by use of the procedure given in NIST 

Technical Note 1297 [41]. The six sources of uncertainties were combined by means of the root 

sum-of-squares of the linear fractional uncertainties averaged over a 400-point frequency 

window. The resulting uncertainties (in decibels) for penetration are plotted in Figure 250 for 

the frequency range from 800 MHz to 18000 MHz. The uncertainties were calculated as a 

function of frequency, and therefore we have listed an approximate average value in the table 

below. The rapid variation is due to the complex cavity environment where some frequencies 

penetrate into the aircraft and are absorbed by the environment, while others do not penetrate. 

We have broken the uncertainties into those below 9 GHz and those above 9 GHz because the 

noise floor resets itself there due to the internal configuration of both attenuators and mixers. 

We believe that a reasonable uncertainty bound would be at the 95 % level for the data shown in 

Figure 250, remembering that this current uncertainty analysis is based on a limited set of data. 

These aircraft are typically measured only once and do not lend themselves to an extensive 

uncertainty analysis. 

Influence factor 

Typical fractional uncertainties (dB) 

< 9 GHz > 9 GHz 

Signal-to-noise 0.05 0.28 

Repeatability 2.83 3.51 

Time gating 1.68 1.00 

Range/distance correction 0.56 0.56 

Extrapolation 1.12 3.43 

Polarization mismatch 0.51 0.51 

Drift 0.09 0.08 

RSS (dB) 4.01 5.27 

Table 21. Typical penetration fractional uncertainties resulting from the six 

influence factors. The signal-to-noise ratio was 65 dB. 
194 

8. Summary and Conclusions 

The data collected in this report will be used to provide guidelines for HIRF testing on various 

aircraft. We have reported on the penetration measurements taken on the FAA’s 737-200 at the 

FAA facility in Atlantic City, New Jersey. The first part of the report discussed the initial 

theoretical analysis and numerical simulations prior to actual measurements. We have discussed 

extrapolation measurements taken to ensure that the measurements are in the far-field of the 

transmitting antenna. We have shown results for measurements taken at various azimuth angles 

around the outside of the aircraft with the receiving antenna in the main passenger cabin and the 

flight deck. We have looked at ground conditions and how they influence the measurements. 

This report also discussed the statistics for a series of internal measurements used to study the 

reverberant field characteristics within various cavities. We see that penetration typically 

decreases as frequency increases. This was an important measurement effort both to aid in 

understanding and to help define standard measurement procedures for HIRF testing. 

The appendices are intended to provide understanding of DRG horn antenna and TEM horn 

antenna boresight gain characteristics, changes in the average power as a function of the number 

of positions measured, statistics for angular measurements for the Bombardier Global 5000 and 

the Beechcraft Premier IA, and numerical studies of the FAA 737-200 internal measurements. 

Figure 250. Combined standard uncertainty in penetration.

0 4000 8000 12000 16000 20000

Frequency (MHz)

0

2

4

6

8

10

RSS Uncertainty (dB)
195 

_____________________________ 

We thank Robert Morrison and Anthony Wilson from the FAA in Atlantic City, New Jersey and 

David Walen from the FAA office in Renton, Washington for their excellent assistance and 

financial support for this work. We also thank John Ladbury of the Field Parameters and EMC 

Applications Project and Jolene Splett of the Statistical Engineering Division at NIST for their 

valuable input into the statistics of reverberation chambers and the general application of 

statistical analysis. 

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2008. 

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versus measurements. IEEE Trans. Electromag. Compat., 43(3):282-293 (August 2001). 

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why classical emc evaluation techniques are becoming obsolete. 2002 Intl Symp. on Electromagnetic 

Compatibility, 2: 648-655 (August 2002). 

 

[23] D. M. Johnson, M. O. Hatfield, G. J. Freyer, RF coupling measurements on passenger aircraft 

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432 (November 1995). 

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Statistics EMC Specif. Design and Clearance, 6:1-7, (May 1992). 

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of electrically large, lossy cavities. Natl. Inst. Stand. Technol. Tech. Note 1361, (September 1993). 

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measurements using the direct illumination technique, 2002 IEEE Symp. Electromag. Compat. 389-394 

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test system. 1993 IEEE Intl. Symp. Electromag. Compat. 116-119 (August 1993). 

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large sources. 2002 IEEE Trans. Electromagnetic Compatibility, 44(1): 79-86 (February 2002). 

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Symp. Electromag. Compat., 2:535-539, (August 2000). 

[31] P. F. Wilson, Emission and Immunity Testing: Test Object Electrical Size and Its Implication. 2004 

IEEE Trans. Electromagnetic Compatibility, 2: 349-352 (August 2004). 

[32] D. Novotny, et.al. Details for Processingg Directional Shielding Measurements of Leaky 

Reverberant Cavities. 2009 Intl. Symp. On Electromagnetic Compatibility, (August 2009). 

[33] Website http://www.we-intl.com/rfoil.html accessed 1/21/09. 

 

[34] C. A. Grosvenor, R. T. Johnk, D.R. Novotny, S. Canales, B. Davis, J. Veneman, TEM horn antenna 

design principles. Natl. Inst. of Stand. Techn. Technical Note 1544. (January 2007). 

[35] J. Graham, D. Hibbard, D.Martin, S. Yencer, D. Novotny, C. Grosvenor, N. Canales, R. Johnk, L. 

Nagy, T. Roach, Outdoor vehicular test range turntable impact on electric-field uniformity study. 2008 

IEEE Symp. Electromag. Compat., 1-6, (August 2008).

[36] R. Johnk, D. Novotny, C. Grosvenor, N. Canales, J. Graham, D. Martin, S. Yencer, D. Hibbard, T. 

Roach, L. Nagy, An electric-field uniformity study of an outdoor vehicular test range. 2006 IEEE Symp. 

Electromag. Compat., 2:404-409, (August 2006). 

[37] R. T. Johnk, B. Archambeault, D. Novotny, Using joint time-frequency analysis to enhance timedomain numerical emc simulations. 2003 Annual Report Interference Technology (2003). 

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[39] R. C. Wittmann, M. H. Francis, L. A. Muth, R. L. Lewis, Proposed uncertainty analysis for RCS 

Measurements. Natl. Inst. Stand. Technol. NISTIR 5019 (January 1994). 

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[41] B. N. Taylor, C. E. Kuyatt, Guidelines for evaluating and expressing the uncertainty of NIST 

measurement results. Natl. Inst. Stand. Technol. Tech. Note 1297 (September 1994). 

[42] E. B. Larsen, R. L. Ehret, D. G. Camell, G. H. Koepke, Calibration of antenna factor at a ground 

screen field site using an automatic network analyzer. 1989 Intl. Symp on Electromagnetic Compatibility, 

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Tech. Note 1392, (February 1998). 
198 

Appendix A: TEM and DRG Horn Boresight Gain Characteristics 

The DRG and TEM horn antennas used in this effort were calibrated before we deployed our 

system in Atlantic City. This technique can be used to derive antenna gain with a specified 

resistive load (typically 50 ) at the antenna terminals. An accurate method for doing this is the 

three-antenna method. As the name implies, three transmission measurements are made with 

three combinations of the three antennas. This procedure is described in detail in reference [42]. 

This process yields three equations that can be readily solved for either gain or antenna factor. 

The gain characteristics of our DRG horn antennas are shown in Figure A1; those for our 36 cm 

TEM horns are shown in Figure A2; and those for our 1.2 m TEM horns are shown in Figure A3. 

The gains displayed in these figures include the antenna input mismatch, which accounts for the 

reduction of gain at the lower frequencies. The DRG horn antenna gain, plotted in Figure A1 

shows that the low-frequency cutoff of these antennas occurs around 750 MHz. As the 

frequency is reduced, the input mismatch increases, which accounts for a rapid decrease in 

antenna gain. Mismatch and gain are not cause and effect, but a combination of both aperture 

beam forming and a better input match accounts for the increasing gain at the higher frequencies. 

A maximum gain of approximately 15 dB occurs at 16,000 MHz. The 36 cm antenna results, 

which are plotted in Figure A2, show a maximum gain of approximately 7 dB realized at 

4,000 MHz. Results for a NIST 1.2 m horn antenna are plotted in Figure A3. This horn is 

longer, and it has a resistive taper, which improves the low-frequency performance. The 

maximum frequency of this antenna is 1500 MHz, due to balun performance limitations, and a 

maximum gain of 7 dB occurs at this frequency as well. 

0 4000 8000 12000 16000 20000

Frequency (MHz)

-20

-10

0

10

20

Antenna Gain (dB)

Horn 1

Horn 2

Horn 3

Figure A1. Measured boresight antenna gain for a DRG horn antenna. The gains plotted here 

include the input mismatch effects, which account for the rapid decrease below 750 MHz.
199 

Figure A2. Measured boresight antenna gain for three identical NIST 36 cm TEM horn antennas. The 

gains plotted here include the input mismatch effects, which account for the rapid decrease below 100 

MHz.

Figure A3. Measured boresight antenna gain for a NIST 1.2 m TEM horn antenna. The gains 

plotted here include the input mismatch effects, which account for the rapid decrease below 50 

MHz.
200 

Appendix B. Number of Positions vs. Average Power 

In Section 6.3.2 we showed that to fully characterize the Bombardier Global 5000 around one 

plane of the aircraft, the number of positions required is 1197 at 1 GHz, 5973 at 5 GHz, and 

21505 at 18 GHz. Since this is in practice impossible to achieve, we decided to look at the 

statistics and average power as a function of position for the Bombardier Global 5000. The goal 

is to provide data as a function of the number of positions and frequencies and how the average 

power seen by the aircraft changes. 

For this analysis we randomly chose measured positions around the aircraft, computed the 

average for these measurements and then added more positions, computed the average, etc. For 

the first computation, we chose 6 angular positions, which included the following angular 

positions, (1) 0°, (2) 40°, (3) 90°, (4) 135°, (5) 180°, and (6) 345°. We then added 2 more 

angular positions, (7) 120°, (8) 20° for a total of 8 positions. For a ten position average we 

added the angular positions (9) 150°, and (10) 60°. We added the following angular positions for 

a 13 position average: (11) 330°, (12) 70°, and (13) 110°. For a 17-position average, these 

additional angular positions were added: (14) 125°, (15) 160°, (16) 340°, and (17) 190°. Adding 

the following five angular positions results in a 22-position average: (18) 30°, (19) 100°, (20) 

140°, (21) 170°, (22) 350°. And finally for all 29 positions, we computed the average by adding 

the final 7 angular positions: (23) 10°, (24) 50°, (25) 80°, (26) 130°, (27) 145° (28) 335°, (29) 

355°. A plot showing how the penetration changes as a function of angular position is shown in 

Figure B1. Whisker Box plots are shown in Figure B2 for various included angular positions. 

This shows that as more positions are included in the average, the median, maximum, and 

minimum values do not vary by more than a few decibels at the frequencies shown. We then 

wanted to look at how the average power changes as more positions are added and this plot is 

shown in Figure B3 as a function of frequency and the number of included positions. We see 

that at approximately 17 included positions the average value tends to approach some constant 

value. Further research needs to be done on this analysis, because this was done on just one 

aircraft. 
201 
202 

Figure B2. Whisker-Box plots showing how the median changes as a function of frequency and number of added positions.

6 Positions

‐80.00‐70.00‐60.00‐50.00‐40.00‐30.00‐20.00‐10.00

0.00

Group 1

‐ 1 GHz

Group 2

‐ 3 GHz

Group 3

‐ 5 GHz

Group 4

‐ 8 GHz

Group 5

‐ 10 GHz

Group 6

‐ 13 GHz

Group 7

‐ 17.5

GHz

(a)

‐80.00‐70.00‐60.00‐50.00‐40.00‐30.00‐20.00‐10.00

0.00

Group 1

‐ 1 GHz

Group 2

‐ 3 GHz

Group 3

‐ 5 GHz

Group 4

‐ 8 GHz

Group 5

‐ 10 GHz

Group 6

‐ 13 GHz

Group 7

‐ 17.5

GHz

10 Positions

(b)

‐80.00‐70.00‐60.00‐50.00‐40.00‐30.00‐20.00‐10.00

0.00

Group 1

‐ 1 GHz

Group 2

‐ 3 GHz

Group 3

‐ 5 GHz

Group 4

‐ 8 GHz

Group 5

‐ 10 GHz

Group 6

‐ 13 GHz

Group 7

‐ 17.5

GHz

17 Positions

(c)

29 Positions

‐80.00‐70.00‐60.00‐50.00‐40.00‐30.00‐20.00‐10.00

0.00

Group 1

‐ 1 GHz

Group 2

‐ 3 GHz

Group 3

‐ 5 GHz

Group 4

‐ 8 GHz

Group 5

‐ 10 GHz

Group 6

‐ 13 GHz

Group 7

‐ 17.5

GHz

(d)
203 

Appendix C. Whisker-Box Plots for Bombardier Global 5000 and HawkerBeechcraft Premier IA 

Throughout the first part of this report, we have presented whisker-box plots of the insertion loss 

as a function of position for various compartments in the aircraft. In this appendix, we would 

like to present whisker-box plots for some of the angular scans of the measurements on the 

Bombardier Global 5000 and the Hawker-Beechcraft Premier IA. These plots provided insight 

into the spread of data and the maximum and minimum values at each position around the 

aircraft. Also, it shows how the data change as the averaging bandwidth changes. 

Figures C1, C2, and C3 show whisker-box plots for the Bombardier Global 5000 with the 

receiving antenna in the main passenger cabin for results centered at 1000 MHz over a 50 MHz 

bandwidth, a 100 MHz bandwidth, and a 200 MHz bandwidth. If we track one angular position 

of 50° across all three bandwidths we derive the statistics shown in Table C1. We see that the 

data change the most from a 50 MHz bandwidth to a 100 MHz bandwidth. The median changes 

from −14.42 dB to −12.60 dB, the maximum changes from −8.42 dB to −6.57 dB, and the 

minimum changes from −20.14 dB to −36.16 dB, and the spread in the data from the 25th

percentile to the 75th percentile changes from 4.10 dB to 5.23 dB. The statistics stay the same in 

looking at a 100 MHz bandwidth around 1000 MHz to a 200 MHz bandwidth. Let’s look at 

another angular position of 180° in Table C2. We see the data change the most from a 50 MHz 

bandwidth to a 100 MHz bandwidth, although less at this angle. The median changes from 

−26.67 dB to −25.76 dB, the maximum changes from −21.30 dB to −15.92 dB, the minimum 

does not change, and the spread in the data from the 25th percentile to the 75th percentile changes 

5 10 15 20 25 30

# Positions included in Average

-24

-20

-16

-12

-8

Average Power (dB)

1 GHz

3 GHz

5 GHz

8 GHz

10 GHz

13 GHz

Figure B3. The average power as a function of frequency 

and number of added positions.
204 

from 5.42 dB to 6.14 dB. The statistics stay the same for the maximum and the minimum when 

changing from the 100 MHz bandwidth at 1000 MHz to the 200 MHz bandwidth. The other 

changes are small compared to the first comparison. We typically use a 200 MHz frequency 

averaging bandwidth to smooth the data for the DRG horn antennas and we typically use a 

50 MHz frequency averaging for the TEM horn antennas. 

Let’s look at some data for the TEM horn antenna in Figures C4, C5, and C6. Figures C4, C5, 

and C6 show whisker-box plots for the Beechcraft Premier IA with the receiving antenna in the 

main passenger cabin for results centered at 1000 MHz over a 50 MHz bandwidth, a 100 MHz 

bandwidth, and a 200 MHz bandwidth. If we track one angular position of 50° across all three 

bandwidths we derive the statistics shown in Table 3. We see that the data change the most from 

a 50 MHz bandwidth to a 100 MHz bandwidth. The median changes from –5.35 dB to 

−5.08 dB, the maximum changes from −2.36 dB to −1.71 dB, and the minimum does not 

change, and the spread in the data from the 25th percentile to the 75th percentile changes from 

4.09 dB to 3.07 dB. When the bandwidth changes from 100 MHz to 200 MHz, the median 

changes from –5.08 dB to −5.84 dB, the maximum does not change, and the minimum changes 

from −20.85 dB to −23.64 dB, and the spread in the data from the 25th percentile to the 75th

percentile changes from 3.94 dB to 4.07 dB. Let’s look at another angular position of 180° in 

Table 4. We see the data change the most from a 50 MHz bandwidth to a 100 MHz bandwidth, 

although less at this angle. The median changes from −9.45 dB to −11.38 dB, the maximum 

changes from −5.35 dB to −5.21 dB, the minimum does not change and the spread in the data 

from the 25th percentile to the 75th percentile changes from 0.40 dB to 6.14 dB. The statistics 

stay the same for the maximum and the minimum when changing from the 100 MHz bandwidth 

at 1000 MHz to the 200 MHz bandwidth. The other changes are small compared to the first 

comparison. 

Table C1. Data statistics for the Bombardier Global 5000 at an angular position of 50o for three 

bandwidths of 50 MHz, 100 MHz, and 200 MHz. 

Bandwidth 

(MHz)

Median 

(dB)

25th percentile

(dB)

75th percentile

(dB)

Maximum

(dB)

Minimum

(dB)

50 −14.42 −15.83 −11.73 −8.42 −20.14

100 −12.60 −15.83 −10.60 −6.57 −36.16

200 −12.60 −15.83 −10.60 −6.57 −36.16
205 

Table C2. Data statistics for the Bombardier Global 5000 at an angular position of 180o for three 

bandwidths of 50 MHz, 100 MHz, and 200 MHz. 

Bandwidth 

(MHz)

Median 

(dB)

25th percentile

(dB)

75th percentile

(dB)

Maximum

(dB)

Minimum

(dB)

50 −26.67 −30.14 −24.72 −21.30 −54.69

100 −25.76 −29.35 −23.21 −15.92 −54.69

200 −25.98 −30.09 −23.20 −15.92 −54.69

Table C3. Data statistics for the Beechcraft Premier IA at an angular position of 50o for three bandwidths 

of 50 MHz, 100 MHz, and 200 MHz. 

Bandwidth 

(MHz)

Median 

(dB)

25th percentile

(dB)

75th percentile

(dB)

Maximum

(dB)

Minimum

(dB)

50 −5.35 −8.03 −3.94 −2.36 −20.85

100 −5.08 −7.03 −3.96 −1.71 −20.85

200 −5.84 −8.25 −4.31 −1.71 −23.64
206 

 

Figure C1. Whisker-box plots for the Bombardier Global 5000 with the receiving antenna in the main passenger cabin, showing results for the transmitting DRG horn antennas in the vertical polarization. These results cover a 50 MHz bandwidth centered around 1000 MHz.
207 

Figure C2. Whisker-box plots for the Bombardier Global 5000 with the receiving antenna in the main passenger cabin, showing results for the transmitting DRG horn antennas in the vertical polarization. These results cover a 100 MHz bandwidth centered around 1000 MHz.
208 

Figure C3. Whisker-box plots for the Bombardier Global 5000 with the receiving antenna in the main passenger cabin, showing results for the transmitting DRG horn antennas in the vertical polarization. These results cover a 200 MHz bandwidth centered around 1000 MHz.
209 

Figure C4. Whisker-box plots for the Beechcraft Premier IA with the receiving antenna in the main passenger cabin, showing results for the transmitting TEM horn antennas in the horizontal polarization. These results cover a 50 MHz bandwidth centered around 1000 MHz.
210 

Figure C5. Whisker-box plots for the Beechcraft Premier IA with the receiving antenna in the main passenger cabin, showing results for the transmitting TEM horn antennas in the horizontal polarization. These results cover a 100 MHz bandwidth centered around 1000 MHz.
211 

Figure C6. Whisker-box plots for the Beechcraft Premier IA with the receiving antenna in the main passenger cabin, showing results for the transmitting TEM horn antennas in the horizontal polarization. These results cover a 200 MHz bandwidth centered around 1000 MHz.
212 

Appendix D: Numerical Modeling of the 737-200 

We have developed a numerical simulation study in order to help with our understanding of the 

propagation of electromagnetic fields both within and coupling to the outside of aircraft. This is 

intended to help us and the FAA understand more fully the impact of HIRF testing and HIRF 

field levels upon aircraft structures. We began with a well-characterized artifact that can be both 

measured and simulated in order to compare measurement with the model. We found that the 

model and the measurements agree to within some numerical error. We then adopted aircraft 

simulations by first developing a rectangular model and then later developing more complex 

structures that simulate a more realistic environment. Simulations in the present paper were 

completed at a frequency of 1 GHz but similar analyses could be extended to other frequencies. 

The only limitation at higher frequencies would be the increasing mesh size. We found that as 

the antenna is moved around inside the aircraft, the field behavior and propagation behavior 

change significantly. We also found that the seats inside the aircraft provide a certain amount of 

attenuation for the fields, and the apertures to the cargo bay help diffuse the fields inside the 

main cabin. For a dipole in the aft main cabin, the field levels from the dipole to the front of the 

main cabin drop from 100 V/m to 0.1 V/m. The propagation in the main cabin is also 

significantly impeded as the dipole is placed in the aft cargo bay. As we model the impact of 

windows, we find that leakage to the outside is not the same for every window; in other words, 

energy does not leak out of the windows equally; there is definite constructive and destructive 

interference that impacts the far-field radiation pattern of the aircraft. This changes as the 

transmitting antenna is moved around inside the aircraft. 

Although a direct comparison to measured data are not available at this time, we do see the value 

of doing these types of measurements when confronting the validity of HIRF measurements and 

understanding the impact of testing procedures. 

This work summarizes the initial numerical modeling studies undertaken to help us understand 

the interior aircraft propagation and to design test methodologies to address insight given here. 

The first task involved measuring and modeling a reference box artifact designed to provide a 

shielding value of approximately 20 dB (see Section 3). We compared the measurements and the 

model to give us confidence that the numerically modeled results are realistic. Using the model 

we can look at pattern effects, radiation effects and the complex field behavior set up inside the 

aircraft. The second section of this appendix shows the development of the aircraft model used 

to simulate the FAA’s 737-200. The model builds up the aircraft from a basic structure and 

adds components such as compartments, seats, and windows until the final model is developed. 

The software used to model the aircraft is a high-performance, full-wave electromagnetic field 

simulator using finite-element tetrahedra. In this package we can integrate the simulation, 

visualization, and solid modeling to obtain a complete picture of the simulated object. A threedimensional model is drawn, material properties, input/output ports, boundaries are defined, and 

post-processing is used to look at either the S-parameters at certain ports or the fields on certain 

cut planes. Automatic meshing is used to further divide the region as the convergent criteria are 

approached. 
213 

Appendix D1. The Reference Box Artifact 

The measurements taken on the reference box, discussed in Section 3.1, were compared to a 

simulated reference box, and the results are briefly discussed here. We used the simulations to 

compare simulated and measured radiation patterns to ensure correctness of modeling software. 

A wire diagram of the simulated artifact with antennas is shown in Figure D1. 

 

Because of the isotropic design of the box, we assume the measured radiation from the box is 

nearly uniform, with respect to angle. We do not assume this would hold true if holes were 

drilled on only one side of the box. We measured the box in four different environments: (1) the 

NIST reverberation chamber, with large modal density, (2) a large, enclosed industrial facility 

having some reverberant behavior, (3) the NIST anechoic chamber with virtually no 

environmental scattering [25–26], and (4) the NIST cone and ground plane facility located at 

NIST-Boulder, although in this case the cone was not used to generate a standard field for these 

measurements [43]. We built several models using varying paddle positions and then examined 

the complexity of the fields within the box and the radiation emanating from the 5 holes at the 

top of the box. This is shown in Figure D2. For the measurements we used a rotatable paddle 

and DRG horn antenna on the inside of the box and a DRG horn antenna on the outside of the 

box. We can see from Figure D2 the field complexity within the box and the complex radiation 

pattern outside the box. To simplify the model we replaced the dual-ridged horn within the box 

with a small dipole. This is a reasonable substitution, because in reverberation theory the gain of 

the antenna within the box is irrelevant and therefore simplifying the antenna reduces our solve 

time and allows us to use less memory in the model. Figure D3 shows the complex field 

behavior at the plane of the apertures, and Figure D4 shows the complex field behavior within 

and outside of the box with a dipole antenna as the source. 

This particular model was created to simulate the measurements made in the lab. Figure D5 is a 

diagram showing the measurement setup in the lab. Measurements were taken at a distance of 

1 m and 3 m away from the box with the 5 open radiation apertures of the box pointed upward 

(out through the page). The results of these measurements are shown in Figure D6, and the 

simulated radiated pattern is shown in Figure D7. We can see that the measured and simulated 

patterns are nearly identical in character. The radiation from the bottom of the box is less than 

that from the top of the box, where the radiating apertures are located. The patterns are not 

identical, possibly due to the apertures not being positioned exactly or other small variations in 

the model; however, they are similar enough that we feel the model is adequate to describe the 

complex field behavior in a realistic way. 
214 

Figure D1. Wire diagram of simulated shielding artifact.

DRG horn antennas

paddle

Holes in box

Figure D2. Complex field behavior inside simulated shielding artifact.
215 

Figure D3. Dipole replacing dual-ridged guide antenna in shielding artifact.

dipole

Figure D4. Complex field behavior in shielding artifact with 

DRG horn antenna replaced by dipole.
216 

Ground Plane

1 m

3 m

Antennas

Rotator Box

Styrofoam

Tower

Figure D5. Measurement setup for shielding artifact.

Figure D6. Measured radiation pattern from shielding artifact.
217 

Figure D7. Simulated radiation pattern with 5 open apertures.
218 

Appendix D2. Simulation of the FAA’s 737-200 

We started the aircraft simulation model by placing a dipole into a simple rectangular box both 

with and without an aperture. The dipole is half-wavelength dipole resonant at 1 GHz, so the 

physical size is 15 cm. We saw that modal structure inside the box without the aperture could be 

affected by energy leaking in through a fairly large aperture in the side of the box when an 

aperture was included. For the next stage of development, the rectangular box was scaled to a 

rough approximation of the actual aircraft. Figure D8 shows the scaled rectangular box with the 

dipole source located toward the top of the model. Five apertures were added to simulate fields 

coupling to the outside of the model. 

Although the scaled rectangular box is a good canonical model, we decided to develop an 

elliptical model that would be more realistic in terms of possible modal structure inside the 

cavity. A wireframe rendering of this elliptical model is shown in Figure D9. The dimensions of 

the model have been scaled down by a factor of 20, as shown in the figure. This model was 

based on the Boeing 737-200 aircraft located at the FAA Technical Center in Atlantic City, New 

Jersey. As shown in previous photos in Section 6, the aircraft seats were located in the first-class 

section of the aircraft and in the aft section of the aircraft. The seats in the middle section of the 

aircraft had been removed. This arrangement was the basis for our model. The seats were 

assigned a dielectric constant of about 2.6 in later models, and a bulk conductivity of 

1x10−16 Siemens/m, which are the values for polyethylene, a low-loss foam. We chose to 

eliminate metal backs for the seats, based on current airline standards. 

Dimensional information from drawings of a 737-600 series aircraft were used because they are 

similar to those for the 737-200 series. The aircraft dimensions of a 737-600 are 31.25 m length, 

3.54 m width and 4.14 m height. We scaled this down by a factor of 20 such that the model 

dimensions are 156.25 cm x 17.7 cm x 20.7 cm. We made the thickness of the aircraft hull 

0.55 cm so that the radius of the inner ellipse is 8.85 cm x 10.35 cm. The hull was assigned 

properties for a perfect electrical conductor (pec) and the interior of the aircraft assigned vacuum 

properties. We do this to simplify the model and create a reference baseline upon which we can 

build. For the actual measurements we used our in-house developed TEM horn antennas and 

commercially available DRG horn antennas; whereas, for the model, we used a center-fed dipole 

antenna for the same reasons as discussed for the previous reference box model. The fuel tank 

sits between the forward and aft cargo bays, and in later models will be completely enclosed by a 

perfect electrical conductor. 

We began with a simple model. Initially there are no coupling apertures to the outside of the 

aircraft. This eliminates the need for a radiation boundary and allows us to investigate the 

addition of various features inside the simulated aircraft before we complicate the model. Figure 

D10 shows one of the first developed models. The floor of the aircraft between the main cabin 

and cargo areas is modeled as a perfect electrical conducting sheet. In the first model, one 

aperture was cut in the center of this sheet. For this and subsequent models there is nothing to 

separate the fields from propagating through the main cabin into the flight deck or into the cargo 

bay areas at the front of the aircraft. In later models, we closed off the flight deck from the cargo 

bay areas but still maintain access from the main cabin, because the actual measurements showed 

that there was not a lot of shielding between the main cabin and flight deck. We set our solution 
219 

frequency at 1 GHz. The modal structure inside in the main cabin is similar to those in the 

rectangular aircraft model, except that these modes have a longer resonant wavelength. Thus, 

the shape of the cavity appears to have an effect on the field structure. The electric fields leak 

through the flight deck and into the cargo bay area, but the fields couple more strongly through 

the single aperture in the floor. As we add more apertures, we will see that they become a 

dominant source of leakage into the cargo bays. For the next stage of model development we 

developed a floor structure that more closely approximates the structure found in an aircraft. The 

floor of an aircraft is composed of metal grid work over which a fiberglass panel is laid, creating 

a series of apertures in the floor. Although the exact dimensions of these openings are not 

known for our aircraft, our canonical model can provide a general understanding of the 

propagation and intensity of the fields coupling through these apertures. Figure D11 has the 15 

apertures cut into the metal floor separating the main cabin and the cargo bay areas. This figure 

shows that the field intensity is more uniform in the cargo bay areas than for coupling from a 

single aperture. We also see a modal structure developing within the cargo bay. At this point 

there is still just a single cargo bay area into which fields can couple either from the main cabin 

through the flight deck or through the apertures in the floor. A 3-dimensional view of the fields 

is shown in Figure D12. The cuts are taken in the XZ and YZ planes of the dipole main 

cabin/cargo bay area. One of the first things we notice is that even though the dipole is located 

in the forward main cabin, we get a strong electric field at the back of the aircraft, due to moding. 

This tells us that a source in the front of the aircraft can create high field levels at the rear of the 

aircraft, and the fields can also appear at other vulnerable parts of the aircraft. 

The next step in the creation of the model was to incorporate seats with the properties discussed 

above. We began by locating six seating areas in the “first class” section. We did not create 

individual seats but merely fused the three seats together to approximate the actual seating areas. 

We were also able to turn off certain apertures in the floor to simulate the forward and aft cargo 

bays without creating hard boundaries. Figure D13 is a wireframe model showing the six seats 

of polyethylene whose loss characteristics are given above. There are six apertures in the floor 

in the forward part of the aircraft to simulate openings to the forward cargo bay. There are nine 

apertures toward the rear of the aircraft to simulate openings to the aft cargo bay. The dipole 

antenna is located in the same position as previous models, and the fields are still allowed to 

couple through the flight deck around to the cargo bay areas. Adding a finite number of seats to 

the main cabin results in energy being lost from the fields, and so less fields propagate toward 

the back of the aircraft or down into the cargo bay areas. We see more localized areas of the 

field within the main cabin and cargo bay areas, so we no longer have a uniform field 

distribution inside the aircraft. The wireframe model geometry is shown in Figure D14 for the 

additional seating, and Figure D15 shows the field distribution. The model shows that the field 

distribution in the cargo bay areas now have a different modal structure due to the diminishing 

field strength, and we also see that the fields in the aft part of the main cabin are diminished by at 

least half in the presence of additional seating. We also note that the null in the electric field has 

moved toward the aft main cabin, which results in a longer wavelength and lower resonant 

frequency for the compartment. 

The next stage in our model development was to separate the cargo bay areas into the forward 

cargo bay, the fuel tank, and the aft cargo bay, and look at the coupling into each of these 

individual compartments. During this first separation, we did not isolate the fuel tank completely 
220 

from the main cabin but allowed the fields to penetrate the floor apertures. Figure D16 is a 

rotated view of the geometry along the YZ-plane to give us an idea of where the apertures 

intersect each of the cargo bay areas and how the fields behave when the fields are completely 

isolated from one compartment to the other. Figure D17 is a close-up view of the separation 

between the forward cargo bay and the fuel tank area, and Figure D18 shows the separation 

between the fuel tank area and the aft cargo bay. These views show us that the fields are not 

leaking through the walls of the individual compartments into adjacent compartments. The result 

of introducing more compartments is that the fields are further disrupted, the field levels are 

lower, and the behavior is more complex in the main cabin and cargo bay areas. Figure D19 

shows the full model with the fuel tank isolated from the rest of the aircraft. 

The next phase of the simulation involved creating an aperture to the outside of the aircraft. We 

began by adding just a single window that was approximately the size of the windows on a real 

aircraft, which are 35.6 cm (14 in.) x 35.6 cm (14 in.). We do not see much leakage through this 

small aperture and don’t see much activity on the outside of the aircraft with a single aperture. 

We believe that this is because the window is acting like a waveguide with a cutoff frequency 

below 1 GHz, the solution frequency. We added an array of 10 windows on one side of the 

aircraft but didn’t see much radiation, so we moved to 30 windows on a single side of the 

aircraft. This new model is shown in Figure D20. This is a close-in view of the windows 

closest to the radiating dipole. The field cut was taken in the center of the XZ-plane of the 

windows. We do see that the fields leak through some windows more strongly than others. 

Figure D21 shows the fields closer to the aft section of the aircraft away from the radiating 

dipole and we see that the fields do not appear to leak out of these windows, due to the fact that 

the field levels are lower. Figure D22 is the same model solved at 1.05 GHz. The field structure 

is quite a bit different even for such a small frequency difference. 

The final step in the current step of modeling was to move the dipole around the interior of the 

aircraft as if a cell phone were emitting in different parts of the aircraft to understand field levels. 

The first location for cell phone radiation was in the forward cargo bay, as if someone had left it 

in a piece of luggage. Figure D23 shows the field levels in the XZ-plane cut along the XZ-axis 

of the dipole that is in the lower half of the aircraft. Figure D24 shows the field levels in the 

main passenger cabin for a dipole in the forward cargo bay. The fields in the aft cargo bay have 

made their way from the forward cargo bay, through the main cabin and have entered the aft 

cargo bay through the apertures in the floor. Figure D24 is a YZ-plane cut along the dipole axis 

showing how the fields propagate through the main cabin into the aft cargo bay. We see the field 

levels decrease as the fields propagate from the forward main cabin, possibly first class, through 

the seats and back into the aft of the main cabin. At this point, we have now also isolated the 

forward cargo bay from the flight deck by applying a metal separation, as was done previously to 

separate the cargo bay from the “fuel tank” area. The next thing we did was to move the cell 

phone into the aft cargo bay to look at the field propagation in the same three planes as in the 

previous position. Figure D26 shows the field levels along the XZ dipole plane which show 

fields in the cargo bay areas. The interesting thing is that this position is not reciprocal to the cell 

phone being in the forward cargo bay. There are virtually no fields propagating in the forward 

cargo bay when the cell phone is ringing in the aft cargo bay. 
221 

To obtain a somewhat three-dimensional view, we plotted the XZ/YZ planar cuts to look at the 

fields in the aircraft when the dipole was located in the aft cargo bay, as shown in Figure D26. 

The final location for the dipole (cell phone/source) was to move it toward the rear of the main 

cabin. Finally, we assembled “3D views” of the field distribution along these two planes as 

shown in Figures D27 and D28. Again, there are virtually no fields that make it into the forward 

cargo bay area or the flight deck. Most of the energy is dissipated in the rear of the aircraft and 

the aft cargo bay areas. What was interesting, and zoomed in on in Figure D27, was the 

localized field intensity where the seat locations are in the rear of the aircraft. These are 

specifically pointed out in Figure D28. 

Radiation

boundary

Dipole

5 “windows”

“Aircraft”

Figure D8. Rectangular model of scaled aircraft showing 

modal structure and leakage from five apertures.
222 

L=156.25 cm

h=20.7 cm

w=17.7 cm

Figure D9. Wireframe diagram for elliptical aircraft model with dimensions.

Figure D10. 737 elliptical model with no seats, no cargo bays, and 1 

aperture cut into the floor.
223 

Figure D11. 737 elliptical model with no seats, no cargo bays, 15 

apertures cut into metal floor between main cabin and cargo bay.

apertures

dipole

“main” 

cabin

“flight 

deck”

“cargo bay” 

area

Figure D12. 737 elliptical model with E-field planar cuts along the XZ 

dipole plane and the main cabin/cargo bay YZ axis.
224 

Figure D13. Wireframe model of the 737 elliptical 

model showing model geometry with 6 seats and 15 

apertures. 

apertures in 

floor of aircraft

6 seats in 

“first class”

Figure D14. Wireframe model 737 elliptical model with 15 apertures to 

cargo bay area and 16 polyethylene seats.

apertures in floor 

of aircraft

16 seats
225 

Figure D15. 737 elliptical model with 15 apertures in cargo bay area and 16 polyethylene 

seats.

dipole

seats

forward

cargo bay

“fuel tank”

aft cargo 

bay

apertures to 

cargo bays

Figure D16. Full model with 16 seats, 15 apertures, no windows, and 

separate cargo compartments.
226 

“fuel tank”

seats

forward 

cargo bay dipole

aperture 

location

Figure D17. Close-up view showing separation between forward cargo bay and “fuel tank” 

area.

“fuel tank”

aft cargo bay

aft main cabin

Figure D18. Close-up view of separation between “fuel tank” area , 

the aft cargo bay, and the aft main cabin.
227 

“fuel tank”

aft cargo 

bay

seats

forward 

cargo bay

dipole

Figure D19. Model showing the isolation of the “fuel tank” area from the fields.

Figure D20. Radiation from windows located closest to dipole.
228 

Figure D21 Fields inside and through windows at a solution 

frequency of 1.05 GHz.

dipole

leakage from

windows

Figure D22. Planar cuts along cargo bay and windows at a solution frequency of 1.05 GHz.

Fuel tank

Aft cargo 

bay

dipole

forward

cargo bay
229 

Figure D23. Fields in cargo bay areas, cut along the XZ dipole plane located 

in the forward cargo bay in the lower half of the aircraft.

dipole

Fuel tank

Aft 

cargo bay

Figure D24. Field levels in main cabin with dipole in forward cargo bay. 

The cut is taken along the XZ dipole plane. 
230 

Figure D25. YZ plane cut along dipole axis showing fields propagating 

from aft cargo bay through main cabin and into forward cargo bay.

dipole

Fuel tank

forward

cargo bay

Main cabin

Figure D26. Fields in the XZ and YZ planes with the dipole in the aft cargo bay.

dipole
231 

Figure D28. “3D” view of fields in aircraft with the dipole located in the aft main cabin.

dipole

seats

Figure D27. YZ dipole plane cut with the dipole located in the aft main cabin.

dipole
232 

Figure D29. Zoom-in view of Figure D27 showing increased field intensity in 

the seats of the aircraft.

seats

dipole
233 

Appendix E: 737-200 Measurement Equipment List*

The main equipment used in the evaluation of the Bombardier Global 5000 is listed below: 

 Agilent N5230A PNA-L (300 kHz to 18 GHz) with a maximum of 16001 

frequencies/trace. 

 Hewlett Packard 8753ES VNA (30 kHz to 6 GHz) with a maximum of 1601 

frequencies/trace. 

 Insulated Wire (IW) Cables (4 m to 10 m)—we used phase-stabilized cables to avoid 

phase drift with temperature variations. 

 Miteq Optical Fiber Link MDDR/MDDT (11 GHz version)—this unit has the ruggedness 

and temperature characteristics for field use. 

 Miteq Optical Fiber Link SCMR/SCMT (18 GHz version)—this unit has the ruggedness 

and temperature characteristics for field use. 

 HP 11713A Switch Controller and HP 3781 Switches 

 HP 59306A Relay Actuator 

 HP E3615A DC Power Supply for relay control 

 AML 0120L2403 Amplifier for DRG antennas 

 Harrison 6205 DC Power Supply 

 Two 1.2 m TEM Horn Antennas designed and built at the NIST Boulder Laboratories 

 One 36 cm TEM Horn Antenna designed and built at the NIST Boulder Laboratories 

 Three 3115 DRG Horn Antennas 

 NIST-developed “RADAR” Labview program used to perform time/frequency 

transformations, time gating, and signal processing 

 NIST-developed “multical” Labview program used to perform multiband VNA 

calibrations and to circumvent the limitation of only 16001 frequency points. This 

program permits an arbitrarily large number of frequency points. In practice, we 

typically use as many as 48003 points. 

 

*

 Certain commercial equipment, instruments, or materials are identified in this paper in order to adequately specify 

the experimental procedure. Such identification does not imply recommendation or endorsement by the National 

Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily 

the best available for the purpose. 

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